Revision B:
• MXZ-2A20NA- 1 , MXZ-4A36NA, MSZ-FD,
MSZ-D and MSY-D have been added.
Please void OBT16 REVISED EDITION-A.
No. OBT16
REVISED EDITION-B
SERVICE TECHNICAL GUIDE
Wireless type Models
MS-A•WA
MSZ-A•NA
· MU-A•WA
· MUZ-A•NA
· MUZ-A•NA -
· MUY-A•NA
U
MSY-A•NA
MSZ-FD•NA · MUZ-FD•NA
U
· MUZ-FD•NA -
· MUZ-D•NA
MSZ-D•NA
MSY-D•NA
U
· MUZ-D•NA -
· MUY-D•NA
Inverter-controlled multi system type Models
· MXZ-A•NA
CONTENTS
1. MS MICROPROCESSOR CONTROL··················4
2. MSZ, MSY MICROPROCESSOR CONTROL······7
3. MXZ MICROPROCESSOR CONTROL··············21
1. MS MICROPROCESSOR CONTROL···························································4
Indoor unit models
Outdoor unit models
MS-A09WA
MS-A12WA
MU-A09WA
MU-A12WA
1-1. COOL OPERATION ···············································································4
1-2. DRY OPERATION ··················································································4
1-3. AUTO VANE OPERATION·····································································6
2. MSZ, MSY MICROPROCESSOR CONTROL···············································7
Indoor unit models
Outdoor unit models
MSZ-A09NA
MSZ-A12NA
MSZ-A15NA
MSZ-A17NA
MSZ-A24NA
MSY-A15NA
MSY-A17NA
MSY-A24NA
MSZ-FD09NA MUZ-A09NA
MSZ-FD12NA MUZ-A12NA
MUZ-FD09NA
MUZ-FD12NA
MUZ-D30NA
MUZ-D36NA
MUY-D30NA
MUY-D36NA
MSZ-D30NA
MSZ-D36NA
MSY-D30NA
MSY-D36NA
MUZ-A15NA
MUZ-A17NA
MUZ-A24NA
MUY-A15NA
MUY-A17NA
MUY-A24NA
2-1. COOL OPERATION ··············································································7
2-2. DRY OPERATION ·················································································8
2-3. HEAT OPERATION···············································································8
2-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION ·····················10
2-5. OUTDOOR FAN MOTOR CONTROL·················································11
2-6. AUTO VANE OPERATION··································································11
2-7
2-8
2-9
.
.
.
INVERTER SYSTEM CONTROL························································12
OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT ·····17
EXPANSION VALVE CONTROL (LEV CONTROL)···························18
3. MXZ MICROPROCESSOR CONTROL·······················································21
Outdoor unit models
MXZ-2A20NA
MXZ-3A30NA
MXZ-4A36NA
3-1. INVERTER SYSTEM CONTROL·························································21
3-2. EXPANSION VALVE CONTROL (LEV CONTROL)····························23
3-3. OPERATIONAL FREQUENCY RANGE ··············································29
3-4. HEAT DEFROSTING CONTROL·························································30
3-5. DISCHARGE TEMPERATURE PROTECTION CONTROL·······················30
3-6. OUTDOOR FAN CONTROL ································································30
3-7. PRE-HEAT CONTROL·········································································31
3-8. COOL OPERATION····················································································31
3-9. DRY OPERATION·································································· BACK COVER
3-10
. HEAT OPERATION···························································BACK COVER
3
1
MS MICROPROCESSOR CONTROL
MS-A•WA
MU-A•WA
1-1. COOL ( ) OPERATION
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature
Room temperature minus
Room temperature minus
set temperature (Initial)
set temperature (During operation)
Thermostat
ON
OFF
-1.8 °F or more
less than-1.8 °F
-1.8 °F
-1.3 °F
2. Indoor fan speed control
Indoor fan operates continuously at the set speed by FAN SPEED CONTROL button regardless of the thermostat’s OFF-
ON.
In AUTO the fan speed is as follows.
Room temperature minus
set temperature (Initial)
3.1 °F or more
Room temperature minus
set temperature (During operation)
Fan speed
High
Med.
Low
between 1.8 and 3.1 °F
less than 1.8 °F
5.4 °F
3.1 °F
1.8 °F
3. Coil frost prevention
Temperature control
When the indoor coil thermistor RT12 reads 37 °F or below the coil frost prevention mode starts immediately.
However, the coil frost prevention doesn’t work for 5 minutes since the compressor has started.
The indoor fan operates at the set speed and the compressor stops for 5 minutes.
After that, if the indoor coil thermistor still reads below 37 °F, this mode is prolonged until the indoor coil thermistor reads
over 37 °F.
Time control
When the three conditions as follows have been satisfied for 1 hour and 45 minutes, compressor stops for 3 minutes.
a. Compressor has been continuously operating.
b. Indoor fan speed is Low or Med.
c. Room temperature is below 79 °F.
When compressor stops, the accumulated time is cancelled and when compressor restarts, time counting starts from the
beginning.
Time counting also stops temporarily when the indoor fan speed becomes High or the room temperature exceeds 79 °F.
However, when two of the above conditions (b. and c.) are satisfied again. Time accumulation is resumed.
Operation chart
Example
ON
Compressor
Outdoor fan
OFF
( Continuously at set speed)
Indoor fan
ON
Set temperature and
initial room temperature in dry mode
1-2. DRY ( ) OPERATION
°F
95
Set temperature is as shown on the right chart.
The system for dry operation uses the same refrigerant circuit as the
cooling circuit.
The compressor and the indoor fan are controlled by the room tem-
perature.
By such controls, indoor flow amounts will be reduced in order to
lower humidity without much room temperature decrease.
86
77
68
59
50
50
59
68
77
86
95 °F
Initial room temperature
4
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Room temperature minus
Room temperature minus
set temperature (Initial)
set temperature (During operation)
Thermostat
ON
OFF
-1.8 °F or more
less than-1.8 °F
-1.8 °F
-1.3 °F
2. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
When thermostat OFF (compressor OFF), fan speed becomes Very Low.
In AUTO the fan speed is as follows.
Room temperature minus
set temperature (Initial)
3.1 F or more
Room temperature minus
set temperature (During operation)
Fan speed
High
Med.
Low
between 1.8 and 3.1 F
less than 1.8 F
4.5
F
3.1
F
1.8
F
3. The operation of the compressor and indoor/ outdoor fan
Compressor operates by room temperature control and time control.
Set temperature is controlled to fall 4 °F from initial room temperature.
Indoor fan and outdoor fan operate in the same cycle as the compressor.
•When the room temperature is 73 °F or over:
When the thermostat is ON, the compressor repeats 8 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
•When the room temperature is under 73 °F.
When the thermostat is ON, the compressor repeats 2 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
Operation time chart
Example
ON
Thermostat
OFF
ON
Indoor fan
OFF
ON
Outdoor fan
Compressor
OFF
8 minutes
4 minutes
3 minutes
1 minute
4. Coil frost prevention
Coil frost prevention is as same as COOL mode. (2-1.3.)
The indoor fan maintains the actual speed of the moment. However ,when coil frost prevention works while the compressor
is not operating, its speed becomes the set speed.
5
1-3. AUTO VANE OPERATION
1. Horizontal vane
ECONO COOL (
) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 3.6 °F higher than that in
COOL mode.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger (indoor coil
thermistor).
SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher than that
in COOL mode, the air conditioner can keep comfort. As a result, energy can be saved.
ECONO COOL operation is cancelled when ECONO COOL button is pressed once again or VANE CONTROL button is
pressed or change to other operation mode.
<SWING operation>
In swing operation of ECONO COOL operation mode, the initial air flow direction is adjusted to “Horizontal”.
According to the temperature of indoor coil thermistor at starting of this operation, next downward blow time is decided.
Then when the downward blow has been finished, next horizontal blow time is decided.
For initial 10 minutes the swing operation is performed in table G~H for quick cooling.
Also, after 10 minutes when the difference of set temperature and room temperature is more than 3.6 °F, the swing
operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.
Temperature of indoor
coil thermistor (°F)
Downward blow time Horizontal blow time
(second)
(second)
A
B
C
D
E
F
59 or less
59 to 63
63 to 64
64 to 68
68 to 70
70 to 72
72 to 75
more than 75
2
5
8
11
14
17
20
23
23
20
17
14
11
8
G
H
5
2
6
2
MSZ,MSY MICROPROCESSOR CONTROL
MSZ-A•NA
MSY-A•NA
MUZ-A•NA
MUY-A•NA
MSZ-FD•NA MSY-D•NA
MSZ-D•NA
MUZ-FD•NA MUY-D•NA
MUZ-D•NA
2-1. COOL ( ) OPERATION
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Thermostat
ON
OFF
-1.8 °F or more
less than-1.8 °F
-1.8 °F
-1.3 °F
2. Indoor fan speed control
Indoor fan operates continuously at the set speed by FAN SPEED CONTROL button regardless of the thermostat’s OFF-
ON.
In AUTO the fan speed is as follows.
Room temperature minus
set temperature (Initial)
3.1 °F or more
Room temperature minus
set temperature (During operation)
MSZ-A
MSY-A
Fan speed
High
Med.
Low
between 1.8 and 3.1 °F
less than 1.8 °F
5.4 °F
3.1 °F
1.8 °F
Room temperature minus
set temperature (Initial)
2.7 °F or more
between 1.8 and 2.7 °F
less than 1.8 °F
Room temperature minus
set temperature (During operation)
MSZ-FD
MSZ-D
MSY-D
Fan speed
High
Med.
Low
5.4 °F
2.7 °F
1.8 °F
3. Coil frost prevention
The compressor operational frequency is controlled to prevent the temperature of indoor heat exchanger from falling exces-
sively.
The compressor is turned OFF for 5 minutes when the temperature of indoor coil thermistor continues 37 °F or less for 5
minutes or more.
The indoor fan maintains the actual speed of the moment.
4. Low outside temperature operation
If the outside temperature falls to 64 °F or less during operation in COOL mode, the unit will switch to the low outside tem-
perature operation mode.
<Operation>
(1) Outdoor fan control
The outdoor fan rotation speed slows down to maintain sufficient cooling capacity.
NOTE: Even when the unit is in the "thermostat-off" status under the low outside temperature operation mode, the out-
door fan rotation does not stop.
(2) Dew drop prevention
When the ambient temperature thermistor reads 10 °F (MUZ-A MUY-A MUZ-D MUY-D), -4 °F (MUZ-FD) or less, as
coil frost or dew drop from indoor unit may occur, the compressor turns OFF with the outdoor fan ON for prevention of
them.
(3) Outdoor temperature detecting control
To detect the exact outdoor temperature in this mode, the compressor turns OFF but the outdoor fan stays ON for 3
minutes once 1 hour. If the outdoor temperature rises over 64 °F, the unit goes back to the normal COOL mode. If the
outside temperature stays below 64 °F, the unit continues to run in the low outside temperature operation mode.
Other protections work as well as in the normal COOL mode.
7
Set temperature and
initial room temperature in dry mode
2-2. DRY ( ) OPERATION
°F
95
Set temperature is as shown on the right chart.
The system for dry operation uses the same refrigerant circuit as the
cooling circuit.
The compressor and the indoor fan are controlled by the room tem-
perature.
By such controls, indoor flow amounts will be reduced in order to
lower humidity without much room temperature decrease.
86
77
68
59
50
50
59
68
77
86
95 °F
Initial room temperature
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Thermostat
ON
OFF
-1.8 °F or more
less than-1.8 °F
-1.8 °F
-1.3 °F
2. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
When thermostat OFF (compressor OFF), fan speed becomes Very Low.
In AUTO the fan speed is as follows.
Room temperature minus
set temperature (Initial)
3.1 F or more
Room temperature minus
set temperature (During operation)
Fan speed
High
Med.
Low
between 1.8 and 3.1 F
less than 1.8 F
4.5
F
3.1
F
1.8
F
3. Coil frost prevention
Coil frost prevention is as same as COOL mode. (2-1.3.)
The indoor fan maintains the actual speed of the moment. However ,when coil frost prevention works while the compressor
is not operating, its speed becomes the set speed.
4. Low outside temperature operation
Low outside temperature operation is as same as COOL mode. (2-1.4.)
2-3. HEAT ( ) OPERATION (MSZ)
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Room temperature minus
set temperature (Initial)
less than 3.6 °F
Room temperature minus
set temperature (During operation)
Thermostat
ON
OFF
3.6 °F or more
3.6 °F
3 °F
2. Indoor fan speed control
(1) Indoor fan operates at the set speed by FAN SPEED CONTROL button.
In Auto the fan speed is as follows.
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Fan speed
High
Med.
Low
3.6 °F or more
between 0.4 and 3.6 °F
less than 0.4 °F
3.6 °F 7.2 °F
0.4 °F
3 °F
8
(2) Cold air prevention control
MSZ-A09/12/15/17 MSZ-FD MSZ-D
When the compressor is not operating,
( ) if the temperature of room temperature thermistor is less than 66 °F, the fan stops.
(
) if the temperature of room temperature thermistor is 66 °F or more and
( ) if the temperature of indoor coil themistor is less than 32 °F, the fan stops.
(
) if the temperature of indoor coil themistor is 32 °F or more, the fan operates at Very Low.
When the compressor is operating,
( ) if the temperature of indoor coil themistor is 104 °F or more, the fan operates at set speed.
(
) if the temperature of indoor coil themistor is less than 104 °F and
( ) if heating operation starts after defrosting, the fan stops.
(
(
) if the temperature of room temperature thermistor is 66 °F or less, the fan stops.
) if the temperature of room temperature thermistor is more than 66 °F, the fan operates at Very Low.
NOTE : When 3 minutes have passed since the compressor started operation, this control is released regardless of the
temperature of room temperature thermistor and indoor coil thermistor.
MSZ-A24
When the compressor is not operating,
( ) if the temperature of room temperature thermistor is 59 °F or less, or temperature of indoor coil thermistor is
less than 64 °F, the fan stops.
(
) if the temperature of room temperature thermistor is more than 59 °F, or temperature of indoor coil themistor is
more than 64 °F, the fan operates at Very Low.
When the compressor is operating,
( ) if the temperature of indoor coil themistor is 64 °F or more, the fan operates at set speed.
(
) if the temperature of indoor coil themistor is less than 64 °F and
( ) if heating operation starts after defrosting, the fan stops.
(
(
) if the temperature of room temperature thermistor is 59 °F or less, the fan stops.
) if the temperature of room temperature thermistor is more than 59 °F, the fan operates at Very Low.
NOTE : When 3 minutes have passed since the compressor started operation, this control is released regardless of the
temperature of room temperature thermistor and indoor coil thermistor.
(3) Warm air control (MSZ-FD)
When the following any condition of (a. ~ c.) and the condition of are satisfied at the same time, warm air control
works.
a.) Fan speed is used in MANUAL.
b.) When cold air prevention has been released.
c.) When defrosting has been finished.
When the temperature of indoor coil thermistor is less than 104 °F.
When warm air control works, the fan speed changes as follows to blow out warm air gradually.
Gradation of fan speed in initial
<Time condition>
<Indoor fan speed>
Less than 2 minutes------------ Low
2 minutes to 4 minutes -------- Med.
More than 4 minutes ----------- High or Super high
The upper limit of the fan speed in MANUAL is the set speed.
When the temperature of indoor coil thermistor has been 104 °F or more, or when the set speed has been changed, this
control is released and the fan speed is the set speed.
3. Overload starting
When the room temperature thermistor reads 64 °F or more, the compressor runs with its maximum frequency regulated for
10 minutes after the start-up.
4. Defrosting
(1) Starting conditions of defrosting
When the following conditions a) ~ c) are satisfied, the defrosting starts.
a) The defrost thermistor reads 27 °F or less.
b) The cumulative operation time of the compressor has reached any of the set values (40, 45, 55, 65, 75, 85, 95, 105,
115, 125, 150 minutes.
c) More than 5 minutes have passed since the start-up of the compressor.
Set value of compressor operation time (here in after referred to as defrost interval)
This is decided by the temperature of defrost thermistor, ambient temperature thermistor, and the previous defrosting
time. For example, the first defrost interval is 40 minutes long, and the second is 45 minutes long. The third and sub-
sequent intervals are set to be longer, and less frequent, depending on defrosting time.
…
The third and subsequent defrost intervals follow any of the three patterns 5 or 10 to 20 minutes longer, the same,
…
or 5 or 10 to 20 minutes shorter compared with the previous defrost interval
shortest 40 minutes.
with the longest 125 minutes and the
9
(2) Releasing conditions of defrosting
Defrosting is released when any of the following conditions is satisfied:
a) The defrost thermistor continues to read 50 °F or more (MUZ-A09/12 MUZ-D) / 41 °F or more (MUZ-A15/17 MUZ-FD) /
59 °F or more (MUZ-A24) for 30 seconds.
b) Defrosting time has exceeded 10 minutes.
c) Any other mode than HEAT mode is set during defrosting.
Time chart of defrosting in HEAT mode (reverse type)
<Indoor unit>
horizontal
set position
set speed
set position
set speed
Horizontal vane
Indoor fan
<
horizontal (temperature of indoor coil thermistor 102 °F)
Very Low (temperature of indoor coil thermistor > 64 °F)
OFF
30
seconds
<Outdoor unit>
Maximum frequency
Compressor normal
OFF
30
OFF
30
40
40
seconds seconds
seconds seconds
5 seconds
5 seconds
ON
ON
Outdoor fan
OFF
ON (HEAT)
ON (HEAT)
R.V. coil
(21S4)
OFF (COOL)
2-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION (MSZ)
Once desired temperature is set, unit operation is switched automatically between COOL and HEAT operation.
1. Mode selection
(1) Initial mode
At first indoor unit operates only indoor fan with outdoor unit OFF for 3 minutes to detect present room temperature.
Following the conditions below, operation mode is selected.
If the room temperature thermistor reads more than set temperature, COOL mode is selected.
If the room temperature thermistor reads set temperature or less, HEAT mode is selected.
10
(2) Mode change
In case of the following conditions, the operation mode is changed.
COOL mode changes to HEAT mode when 15 minutes have passed with the room temperature 4 °F below the set
temperature.
HEAT mode changes to COOL mode when 15 minutes have passed with the room temperature 4 °F above the set
temperature.
In the other cases than the above conditions, the present operation mode is continued.
NOTE1: Mode selection is performed when multi standby (refer to NOTE2) is released and the unit starts operation with
ON-timer.
NOTE2: If two or more indoor units are operating in multi system, there might be a case that the indoor unit, which is
operating in AUTO (
of standby.
), cannot change over the other operating mode (COOL
HEAT) and becomes a state
(3) Indoor fan control/ Vane control
As the indoor fan speed and the horizontal vane position depend on the selected operation mode, when the operation
mode changes over, they change to the exclusive ones.
2-5. OUTDOOR FAN MOTOR CONTROL
Fan speed is switched according to the compressor frequency.
<Relation between compressor frequency and fan speed>
Compressor frequency (Hz)
Fan speed
High
Down
Up
Down
Up
MUZ-A
MUY-A
33
44
Low
Min. Compressor frequency Max.
MUZ-FD
33
39
44
54
MUZ-D
MUY-D
2-6. AUTO VANE OPERATION
1. Horizontal vane
(1) Cold air prevention in HEAT operation (MUZ)
When any of the following conditions occurs in HEAT operation, the vane angle changes to Horizontal position automati-
cally to prevent cold air blowing on users.
Compressor is not operating.
Defrosting is performed.
Indoor coil thermistor temperature does not exceed 102 °F within about 3 minutes after compressor starts.
NOTE: When 2 or more indoor units are operated with multi outdoor unit, even if any indoor unit turns thermostat off,
this control doesn’t work in the indoor unit.
(2) ECONO COOL (
) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 3.6 °F higher than that in
COOL mode.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger (indoor coil
thermistor).
SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher than that
in COOL mode, the air conditioner can keep comfort. As a result, energy can be saved.
ECONO COOL operation is cancelled when ECONO COOL button is pressed once again or VANE CONTROL button is
pressed or change to other operation mode.
11
<SWING operation>
In swing operation of ECONO COOL operation mode, the initial air flow direction is adjusted to “Horizontal”.
According to the temperature of indoor coil thermistor RT12 at starting of this operation, next downward blow time is
decided. Then when the downward blow has been finished, next horizontal blow time is decided.
For initial 10 minutes the swing operation is performed in table G~H for quick cooling.
Also, after 10 minutes when the difference of set temperature and room temperature is more than 3.6 °F, the swing
operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.
Temperature of indoor
coil thermistor (°F)
Downward blow time Horizontal blow time
(second)
(second)
A
B
C
D
E
F
59 or less
59 to 63
63 to 64
64 to 68
68 to 70
70 to 72
72 to 75
more than 75
2
5
8
11
14
17
20
23
23
20
17
14
11
8
G
H
5
2
2-7. INVERTER SYSTEM CONTROL
2-7-1. Inverter main power supply circuit
MUZ-A09/12/15/17
MUY-A15/17
MUZ-FD
CURRENT
DIODE
TRANSFORMER
REACTOR
MODULE1
U
U
V
P
NOISE
FILTER
CIRCUIT
RESISTOR
RELAY
+
+
POWER
SUPPLY
~
~
SMOOTHING
CAPACITOR
MS
3~
V
-
N
W
W
IPM
COMPRESSOR
+
~
~
SWITCHING
POWER
TRANSISTOR
DIODE
MODULE2
-
BOOSTER CHOPPER CIRCUIT
Function of main parts
NAME
FUNCTION
INTELLIGENT POWER MODULE (IPM)
SMOOTHING CAPACITOR
CURRENT TRANSFORMER
DIODE MODULE 1
It supplies three-phase AC power to compressor.
It stabilizes the DC voltage and supply it to IPM.
It measures the current of the compressor motor.
It converts the AC voltage to DC voltage.
It absorbs the rush current not to run into the main power supply circuit when
the electricity turns ON.
RESISTOR
RELAY
It short-circuits the resistance which restricts rush current during the normal
operation after the compressor startup.
DIODE MODULE 2
BOOSTER
It improves power factor.
It controls the bus-bar voltage.
SWITCHING POWER TRANSISTOR
CHOPPER
CIRCUIT
REACTOR
12
MUZ-A24
MUY-A24
MUZ-D
MUY-D
CURRENT
TRANSFORMER
REACTOR
U
U
V
P
N
NOISE
FILTER
CIRCUIT
RESISTOR
RELAY
+
POWER
SUPPLY
SMOOTHING
CAPACITOR
MS
3~
PFC
V
W
W
IPM
COMPRESSOR
Function of main parts
NAME
FUNCTION
INTELLIGENT POWER MODULE (IPM)
SMOOTHING CAPACITOR
It supplies three-phase AC power to compressor.
It stabilizes the DC voltage and supplies it to IPM.
It measures the current of the compressor motor.
It measures the current of the main power supply circuit.
CURRENT TRANSFORMER
REACTOR
It rectifies AC, controls its voltage and improves the power factor of power
supply.
POWER FACTOR CORRECTION MODULE (PFC)
RESISTOR
RELAY
It restricts rush current with the resistance.
It short-circuits the resistance which restricts rush current during the compres-
sor operates.
13
2-7-2. Outline of main power supply circuit
MUZ-A09/12/15/17 MUY-A15/17 MUZ-FD
1. At the start of operation
Main power supply circuit is formed when RELAY is turned ON at COMPRESSOR startup.
To prevent rush current from running into the circuit when power supply is turned ON,
RESISTOR is placed in sub circuit.
2. At normal operation
When AC runs into POWER P.C. board, its external noise is eliminated in NOISE FILTER CIRCUIT.
After noise is eliminated from AC, it is rectified to DC by DIODE MODULE 1.
DC voltage, to which AC has been rectified by process , is stabilized by SMOOTHING CAPACITOR and supplied to IPM.
DC voltage, which has been stabilized in process , is converted to three-phase AC by IPM and supplied to COMPRES-
SOR.
CURRENT TRANSFORMER, which is placed in the power supply circuit to COMPRESSOR, are used to measure the val-
ue of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls impressed
voltage and frequency with those information.
3. Purpose of PAM adoption
PAM : Pulse Amplitude Modulation
PAM has been adopted for the efficiency improvement and the adaptation to IEC harmonic current emission standard
Outline of simple partial switching method
In conventional inverter models, DIODE MODULE rectifies AC voltage to DC voltage, SMOOTHING CAPACITOR makes its
DC waveform smooth, and IPM converts its DC voltage to imitated AC voltage again in order to drive the compressor motor.
However, it has been difficult to meet IEC harmonic current emission standard by above circuit because harmonic gets
generated in the input current waveform and power factor gets down. The simple partial switching method with PAM, which
has been adopted this time, places and utilizes BOOSTER CHOPPER CIRCUIT before rectifying AC voltage in the general
passive-method converter circuit. As harmonic gets suppressed and the peak of waveform gets lower by adding BOOSTER
CHOPPER CIRCUIT as mentioned above and by synchronizing the timing of switching with the zero-cross point of waveform,
the input current waveform can be improved and the requirement of IEC harmonic current emission standard can be satisfied.
Since the switching synchronized with the zero cross point, this simple partial switching method has the feature of lower en-
ergy loss compared to active filter method. In addition, output and efficiency is enhanced by combining with vector-controlled
inverter in order to boost the voltage of power supplied to IPM.
Input current waveform without PAM
Input current waveform with PAM
Due to the time of no electricity;
· Power factor gets worse.
· Harmonic gets increased.
Owing to the increase of energized time;
· Power factor gets better.
· Harmonic gets suppressed.
Input current
Input voltage
Energized time is short in
case L inductance is small.
No electricity runs into
diode module because the
voltage at both sides of smoothing
capacitor is higher than input voltage.
14
4. Intelligent power module
IPM consists of the following components
· IGBT (x6)
: Converts DC waveform to three-phase AC waveform and outputs it.
· Drive Circuit
· Protection circuit
: Drives transistors.
: Protects transistors from overcurrent.
Since the above components are all integrated in IPM, IPM has a merit to make the control circuit simplify and miniaturize.
5. Elimination of electrical noise
NOISE FILTER CIRCUIT, which is formed by *CMC COILS capacitors placed on the POWER P.C. board, eliminates electri-
cal noise of AC power that is supplied to main power supply circuit. And this circuit prevents the electrical noise generated in
the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils
MUZ-A24 MUY-A24 MUZ-D MUY-D
1. At the start of operation
Main power supply circuit is formed when RELAY is turned ON at COMPRESSOR startup.
To prevent rush current from running into the circuit when power supply is turned ON, RESISTOR are placed in sub circuit.
2. At normal operation
When AC runs into noise filter P.C. board, its external noise is eliminated in NOISE FILTER CIRCUIT.
After noise being eliminated from AC, it is rectified to DC by REACTOR and PFC. If the operating frequency becomes 25
Hz or more, DC voltage rises to 370 V.
DC voltage, to which has AC been rectified by process , is stabilized by SMOOTHING CAPACITOR and supplied to IPM.
The DC (Bus voltage), which has been stabilized in process , is converted to three-phase AC by IPM and supplied to
COMPRESSOR.
CURRENT TRANSFORMER, which is placed in the power supply circuit to COMPRESSOR, are used to measure the
value of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls im-
pressed voltage and frequency with those information.
3. Power factor improvement
Booster coil reactor and power factor controller rectify AC to DC and control its voltage.
In the motor drive system of sine wave control, power factor can be improved by reducing harmonics. PFC and reactor stabi-
lize the voltage of DC supplied to inverter circuit and make its waveform smooth.
4. Power transistor module
IPM consists of the following components.
· Power Transistors (x6) : Converts DC waveform to three-phase AC waveform and outputs it.
· Drive Circuit
: Drives transistors.
· Protection circuit
: Protects transistors from over current.
Since the above components are all integrated in IPM, IPM has a merit that can get the control circuit simplified and miniatur-
ized.
5. Elimination of electrical noise
NOISE FILTER CIRCUIT, which is formed by *CMC COILS and capacitors placed on the noise filter P.C. board, eliminates
electrical noise of AC power that is supplied to main power supply circuit. In short, common mode noise is absorbed in this
circuit.
Moreover, normal mode noise is absorbed in another NOISE FILTER CIRCUIT which is formed by *NMC COILS and capaci-
tors.
Both NOISE FILTER CIRCUIT exists for preventing the electrical noise generated in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils
*NMC COILS; Normal mode choke coils
15
2-7-3. Sine wave control
In these air conditioners, compressor equips brushless DC motor which doesn't have Hall element.
In short, the motor is sensorless. However, it's necessary to locate the polar direction of rotor in order to drive brushless DC mo-
tor efficiently. The general detection method of the polar direction for such a DC motor is to locate it from the voltage induced by
unenergized stator.
Therefore, it is necessary to have a certain period of time in which the stator is being unenergized for the rotor position detection
when the voltage of supplied power is impressed.
So the motor has been driven by square wave control (the conventional motor drive system) which energizes the motor only
when the range of electrical angle is within 120° because it is forced to be unenergized within 30° at start & end of one heap in
one waveform cycle (180°) when the voltage is impressed.
However, torque pulsation occurs at rotation in this method when the current-carrying phases are switched over to other phases
in sequence. Therefore, sine wave control system is adopted for these air conditioners because it can make the phase-to-phase
current waveform smoother (sine wave) in order to drive the motor more efficiently and smoothly.
2-7-4. Characteristics of sine wave control in case of brushless DC motor
Although ordinary three-phase induction motor requires energy to excite the magnetic field of rotor, brushless DC motor
doesn't need it. So, higher efficiency and torque are provided.
●
This control provides the most efficient waveform corresponding to the rotation times of compressor motor.
The rotation can be set to higher compared to the conventional motor drive system. So, the time in which air conditioner
can be operated with energy saved is longer than conventional models. This can save annual electric consumption.
●
●
Compared to square wave control, the torque pulsation is reduced at rotation so that the motor operates more quietly.
Since response and efficiency of motor are enhanced in sine wave control, finer adjustment can be provided.
●
●
DC Motor
Permanent magnet is embedded
Necessary
AC Motor
Excited by magnetic field of stator
Unnecessary
Rotor
Rotor Position Signal
In brushless DC motor, permanent magnet is embedded in the rotor. Therefore, it doesn't require energy to excite the rotor
like AC motor does. However, it's necessary to control the frequency of three-phase AC current supplied to the stator accord-
ing to the polar direction of magnet embedded in the rotor so as to drive the motor efficiently. Controlling 3 phase AC current
frequency also means controlling the timing to switch the polarity of stator. Therefore, the polar direction of rotor needs to be
detected.
2-7-5. Control Method of Rotation Times
Sine wave control makes the current transformers conduct real time detection of the value of the current running into the mo-
tor, locates the rotor position from the detected value, and decides if voltage should be impressed and if frequency should be
changed.
Compared to the conventional control and rotor position detection method, sine wave control can provide finer adjustment of the
voltage of supplied power. The value of the current running into the motor is determined by each motor characteristic.
16
2-8. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT
1. Outline
The operational frequency is as following:
First, the target operational frequency is set based on the difference between the room temperature and the set tem-
perature.
Second, the target operational frequency is regulated by discharge temperature protection, high pressure protection,
electric current protection and overload protection and also by the maximum/minimum frequency.
2. Maximum/minimum frequency in each operation mode.
Unit: Hz
COOL
HEAT (MUZ)
DRY
Applied model
Minimum Maximum Minimum Maximum Minimum Maximum
frequency frequency frequency frequency frequency frequency
MUZ-A09
MUZ-A12
32
32
70
73
32
32
76
71
32
32
57
57
MUZ-A15
MUY-A15
MUZ-A17
MUY-A17
MUZ-A24
MUY-A24
10
10
15
82
87
15
15
15
93
93
10
10
15
68
68
110
108
102
MUZ-FD09
MUZ-FD12
MUZ-D30
MUY-D36
MUZ-D36
MUY-D36
10
10
20
20
20
20
52
62
84
79
91
92
10
10
20
—
20
—
100
100
87
10
10
20
20
20
20
41
41
83
79
83
79
—
94
—
The operation frequency in COOL mode is restricted by the upper limit frequency after 1 hour or 0.5 ~ 1 hour as
shown below for dew prevention.
It is rated frequency or less.
Maximum
frequency
Upper limit
1 hour
frequency
or
Rated frequency or less
Time
0.5~1 hour
17
2-9. EXPANSION VALVE CONTROL (LEV CONTROL)
(1) Outline of LEV control
The LEV basic control is comprised of setting LEV opening degree to the standard opening °F set for each operational
frequency of the compressor. However, when any change in indoor/outdoor temperatures or other factors cause air con-
ditioning load fluctuation, the LEV control also works to correct LEV opening degree based on discharge temperature
(Shell temperature) of the compressor, developing the unit’s performance.
Minimum
: 33 pulse (MUZ-A09/12/15/17 MUY-A15/17)
59 pulse (MUZ-A24 MUY-A24)
54 pulse (MUZ-FD)
Control range
58 pulse (MUZ-D MUY-D)
: 500 pulse
Maximum
Open : 40 pulse/second
Close : 90 pulse/second.
Actuating speed
Opening degree adjustment
LEV opening degree is always adjusted in opening direction.
(When reducing the opening degree, LEV is once over-closed,
and then adjusted to the proper degree by opening.
Unit OFF
LEV remains at maximum opening degree (reaches maximum
opening degree approximate in 15 minutes after compressor
stops)
Remote controller ON
LEV is positioned. (first full-closed at zero pulse and then posi-
tioned.)
COOL · DRY MODE
During 1 to 5 minutes after compressor starts
LEV is fixed to standard opening degree according to opera-
tional frequency of compressor.
HEAT MODE
During 1 to 15 minutes after compressor starts
More than 5 (COOL, DRY), 15 (HEAT (MUZ)) minutes LEV opening degree is corrected to get target discharge tem-
have passed since compressor start-up
perature of compressor.
(For lower discharge temperature than target temperature,
LEV is corrected in closing direction.)
(For higher discharge temperature than target temperature,
LEV is corrected in opening direction.)
It may take more than 30 minutes to reach target tempera-
ture, depending on operating conditions.
Thermostat OFF
Thermostat ON
LEV is adjusted to exclusive opening degree for thermostat
OFF.
LEV is controlled in the same way as that after the compres-
sor has started up.
Defrosting in HEAT mode
LEV is adjusted to open 500 pulse.
18
(2) Time chart
Air conditioner OFF
(thermostat off)
Air conditioner ON
Positioning
Opening degree is
corrected according
to discharge
Standard
opening
degree
Commanded
to open
temperature.
about 5 minutes <COOL, DRY>
about 15 minutes <HEAT>
Time
ON
OFF Time
(3) Control data
06
05
F
E
D
04
03
02
01
C
B
A(target discharge temperature)
(Hz)
30
50
70
90
110
130
Operational frequency of the compressor
(a) Reference value of target discharge temperature
(COOL / HEAT (MUZ) F)
Applied model
A
B
C
D
E
F
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
122
113
129
120
140
140
120
109
126
131
127
126
136
136
140
145
131
124
135
140
140
138
147
151
140
149
142
138
149
149
151
154
158
165
145
153
153
156
167
154
158
169
158
180
147
158
162
167
183
162
158
169
158
185
153
158
169
176
187
167
MUZ-A09/12
MUZ-A15/17
MUY-A15/17
MUZ-A24
MUY-A24
MUZ-FD
MUZ-D
MUY-D
In COOL operation, the two indoor coil thermistors (one main and one sub) sense temperature ununiformity (super
heat) at the heat exchanger, and when temperature difference have developed, the indoor coil thermistors adjust
LEV opening degree to get approximate 10 degrees lower temperature than the target temperature in the table
above, thus diminishing super heat.
19
(b) Reference value of LEV standard opening degree (pulse)
Applied model
A
B
C
D
E
F
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
130
100
290
130
150
130
180
130
150
100
190
130
300
150
166
150
240
180
170
120
240
170
350
220
186
170
300
240
210
140
260
210
350
250
206
196
320
270
250
190
260
230
370
280
230
210
320
300
280
240
260
230
370
300
260
226
320
300
300
280
MUZ-A09/12
MUZ-A15/17
MUY-A15/17
MUZ-A24
MUY-A24
MUZ-FD
MUZ-D
MUY-D
20
3
MXZ MICROPROCESSOR CONTROL
MXZ-A•NA
3-1. INVERTER SYSTEM CONTROL
3-1-1. Inverter main power supply circuit
CURRENT
TRANSFORMER
REACTOR
U
U
V
P
N
NOISE
FILTER
CIRCUIT
RESISTOR
RELAY
+
POWER
SUPPLY
SMOOTHING
CAPACITOR
MS
3~
PFC
V
W
W
IPM
COMPRESSOR
Function of main parts
NAME
FUNCTION
INTELLIGENT POWER MODULE (IPM)
SMOOTHING CAPACITOR
It supplies three-phase AC power to compressor.
It stabilizes the DC voltage and supplies it to IPM.
It measures the current of the compressor motor.
CURRENT TRANSFORMER
It measures the current of the main power supply circuit.
REACTOR
It rectifies AC, controls its voltage and improves the power factor of power
supply.
POWER FACTOR CORRECTION MODULE (PFC)
RESISTOR
RELAY
It restricts rush current with the resistance.
It short-circuits the resistance which restricts rush current during the compres-
sor operates.
3-1-2. Outline of main power supply circuit
1. At the start of operation
Main power supply circuit is formed when RELAY is turned ON at COMPRESSOR startup.
To prevent rush current from running into the circuit when power supply is turned ON, RESISTOR are placed in sub circuit.
2. At normal operation
When AC runs into noise filter P.C. board, its external noise is eliminated in NOISE FILTER CIRCUIT.
After noise being eliminated from AC, it is rectified to DC by REACTOR and PFC. If the operating frequency becomes 25
Hz or more, DC voltage rises to 370 V.
DC voltage, to which has AC been rectified by process , is stabilized by SMOOTHING CAPACITOR and supplied to IPM.
The DC (Bus voltage), which has been stabilized in process , is converted to three-phase AC by IPM and supplied to
COMPRESSOR.
CURRENT TRANSFORMER, which is placed in the power supply circuit to COMPRESSOR, are used to measure the val-
ue of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls impressed
voltage and frequency with those information.
21
3. Power factor improvement
Booster coil reactor and PFC rectify AC to DC and control its voltage.
In the motor drive system of sine wave control, power factor can be improved by reducing harmonics. PFC and reactor stabi-
lize the voltage of DC supplied to inverter circuit and make its waveform smooth.
4. Power transistor module
IPM consists of the following components.
· Power Transistors (x6) : Converts DC waveform to three-phase AC waveform and outputs it.
· Drive Circuit
: Drives transistors.
· Protection circuit
: Protects transistors from over current.
Since the above components are all integrated in IPM, IPM has a merit that can get the control circuit simplified and miniatur-
ized.
5. Elimination of electrical noise
NOISE FILTER CIRCUIT, which is formed by *CMC COILS and capacitors placed on the noise filter P.C. board, eliminates
electrical noise of AC power that is supplied to main power supply circuit. In short, common mode noise is absorbed in this
circuit.
Moreover, normal mode noise is absorbed in another NOISE FILTER CIRCUIT which is formed by *NMC COILS and capaci-
tors.
Both NOISE FILTER CIRCUIT exists for preventing the electrical noise generated in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils
*NMC COILS; Normal mode choke coils
3-1-3. Sine wave control
In these air conditioners, compressor equips brushless DC motor which doesn't have Hall element.
In short, the motor is sensorless. However, it's necessary to locate the polar direction of rotor in order to drive brushless DC mo-
tor efficiently. The general detection method of the polar direction for such a DC motor is to locate it from the voltage induced by
unenergized stator.
Therefore, it is necessary to have a certain period of time in which the stator is being unenergized for the rotor position detection
when the voltage of supplied power is impressed.
So the motor has been driven by square wave control (the conventional motor drive system) which energizes the motor only
when the range of electrical angle is within 120° because it is forced to be unenergized within 30° at start & end of one heap in
one waveform cycle (180°) when the voltage is impressed.
However, torque pulsation occurs at rotation in this method when the current-carrying phases are switched over to other phases
in sequence. Therefore, sine wave control system is adopted for these air conditioners because it can make the phase-to-phase
current waveform smoother (sine wave) in order to drive the motor more efficiently and smoothly.
3-1-4. Characteristics of sine wave control in case of brushless DC motor
Although ordinary three-phase induction motor requires energy to excite the magnetic field of rotor, brushless DC motor
doesn't need it. So, higher efficiency and torque are provided.
●
This control provides the most efficient waveform corresponding to the rotation times of compressor motor.
The rotation can be set to higher compared to the conventional motor drive system. So, the time in which air conditioner can
be operated with energy saved is longer than conventional models. This can save annual electric consumption.
●
●
Compared to square wave control, the torque pulsation is reduced at rotation so that the motor operates more quietly.
Since response and efficiency are enhanced in sine wave control, finer adjustment can be provided.
●
●
DC Motor
Permanent magnet is embedded
Necessary
AC Motor
Excited by magnetic field of stator
Unnecessary
Rotor
Rotor Position Signal
In brushless DC motor, permanent magnet is embedded in the rotor. Therefore, it doesn't require energy to excite the rotor
like AC motor does. However, it's necessary to control the frequency of three-phase AC current supplied to the stator accord-
ing to the polar direction of magnet embedded in the rotor so as to drive the motor efficiently. Controlling 3 phase AC current
frequency also means controlling the timing to switch the polarity of stator. Therefore, the polar direction of rotor needs to be
detected.
3-1-5. Control Method of Rotation Times
Sine wave control makes the current transformers conduct real time detection of the value of the current running into the mo-
tor, locates the rotor position from the detected value and decides if voltage should be impressed and if frequency should be
changed.
Compared to the conventional control and rotor position detection method, sine wave control can provide finer adjustment of the
voltage of supplied power. The value of the current running into the motor is determined by each motor characteristic.
22
3-2. EXPANSION VALVE CONTROL (LEV CONTROL)
Linear expansion valve (LEV) is controlled by “Thermostat ON” commands given from each unit.
Indoor unit status
LEV opening
Stop of all indoor unit
Opening before stop → 500 pulse in 15 minutes
When outdoor unit is operating, COOL : 5 pulse (full closed)
some indoor units stop and some HEAT :(MXZ-2A / 3A30NA) : 140 pulse (slightly opened)
1
:(MXZ-3A30NA-
/ 4A ) : 100 → 59 pulse
operate.
When the outdoor unit operates (When the other indoor unit operates) : 5 pulse.
When outdoor unit stops. (When the other indoor unit stops or thermo off) :
Maintain LEV opening before stop → 500 pulse in 15 minutes
Thermostat OFF in COOL or DRY
mode
• LEV opening for each indoor unit is determined by adding adjustment in accordance
with the number of operating unit and the capacity class to standard opening, based
on the operation frequency:
Ex.) Opening 130 pulse in standard opening 1 → Minimum 80 pulse, Maximum 205
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 3 units operation)
Thermostat ON in COOL or DRY • After starting operation, adjustment in accordance with intake super heat, discharge
mode
temperature is included in standard opening. 1
NOTE: LEV opening in each frequency at DRY operation and COOL operation is the
same. However, velocity and compressor operation frequency controls are differ-
ent. See 3-3. OPERATIONAL FREQUENCY RANGE
(As far as the indoor unit velocity control goes, refer to DRY operation in MICRO-
PROCESSOR CONTROL in indoor unit.)
• When the outdoor unit operates. (When the other indoor unit operates) : 140 pulse.
Thermostat OFF in HEAT mode • When the outdoor unit stops. (When the other indoor unit stops or thermo off) : Main-
tain LEV opening before stop → 500 pulse in 15 minutes. “
• LEV opening for each indoor unit is determined by adding adjustment in accordance
with the number of operating unit and the capacity class to standard opening, based
on the operation frequency:
Ex.) Opening 120 pulse in standard opening 1 → Minimum 70 pulse, Maximum 165
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 3 units operation)
• After starting operation, opening becomes the one that adjustment in accordance with
discharge temperature was added to basic opening. 1 “
Thermostat ON in HEAT mode
1 LEV opening when the outdoor unit is operating: Upper limit 500 pulse, Lower limit 53pulse (MXZ-2A / 3A30NA), 59 pulse
1
(MXZ-3A30NA-
/ 4A).
23
MXZ-2A20NA/3A30NA
The table below shows the role of Exclusive LEV and Receiver LEV in each operation mode.
Discharge
Capacity Distribution Temperature
Protection
Evaporation
Temperature
Protection
Circulation Amount
Control
High Pressure
Protection
Exclusive LEV
Receiver LEV
Exclusive LEV
Receiver LEV
○
×
×
○
○
×
○
×
○
○
○
○
○
○
○
○
○
○
—
—
COOL
HEAT
Outdoor
heat
Indoor heat Exclusive
exchanger LEV
exchanger
Receiver
Receiver
LEV
(MXZ-3A30NA)
In COOL mode, the two indoor coil thermistors (one main and one sub) sense temperature ununiformity (super heat) at the
heat exchanger, and when temperature difference have developed, the indoor coil thermistors adjust LEV opening to dimin-
ish the super heat. This action is called Evaporation Temperature Protection.
The opening pulse of the Receiver LEV is fixed to the standard No.3 in cooling operation, and so is that of each Exclusive
LEV in heating operation.
However the opening pulse will be changed to the standard No.4 or No.5 when the discharge temperature protection or high-
pressure protection is working.
In addition to that, it will also be changed to standard No.2 or No.1 when the opening pulse of the each Exclusive LEV
becomes 100 pulse or less in cooling operation or so does that of Receiver LEV in heating operation.
<MXZ-2A20NA>
Number of
operating
indoor units
LEV opening (pulse)
COOL
HEAT
Standard No.
1 unit
200
300
400
450
500
2 units
1 unit
120
140
160
220
280
2 units
120
140
160
220
1
2
3
4
5
150
320
360
410
500
280
<MXZ-3A30NA>
Number of
operating
indoor units
LEV opening (pulse)
COOL
HEAT
1 unit
2 units
250
320
360
410
3 units
1 unit
2 units
250
300
380
400
3 units
Standard No.
1
2
3
4
5
150
250
350
400
450
250
320
370
420
470
250
300
450
460
470
250
300
380
390
440
460
450
24
Determination of LEV standard opening in each indoor unit
• The standard opening is on the straight line, which connects an each standard point in the section where divided into
seven according to the operation frequency of compressor as shown in the figure below.
(LEV opening is controlled in proportion to the operation frequency.)
NOTE: Opening is adjusted at the standard opening according to the indoor unit conditions.
However, inclination of standard opening in each point of opening does not change with the original curve.
• Add opening provided in Difference in capacity in the table below to the standard opening from 1 to 8, when capacity
of the indoor unit is excluding code 1.
• Add opening provided in Difference in operation number in the table below to determined LEV opening for each
indoor unit, when 2 or 3 indoor units are operated at the same time.
NOTE: Even when the adjusted standard opening exceeds the driving range from 59 to 500 pulse, actual driving out-
put opening is in a range from 59 to 500 pulse.
4Hz
10
09
08
07
06
05
04
03
02
01
23 38 54 69 84 100 115 131 146 MXZ-2A
14 23 32 41 50 59 68 77 86 MXZ-3A/4A
Compressor operating frequency (Hz)
MXZ-2A20NA
Standard opening (pulse)
LEV Opening (code)
COOL
1
2
3
4
5
6
7
8
9
10
120 130 136 146 156 160 170 180 190 200
100 110 120 130 146 160 170 180 190 200
HEAT
Difference in capacity
Difference in operation number
Code3,4 Code5,6 Code7,8 Code9,10 Code11,12 Code13,14 Code15or above
2
-20
0
COOL
HEAT
3
3
6
6
9
9
12
52
15
55
25
65
35
75
MXZ-3A30NA
Standard opening (pulse)
LEV Opening (code)
COOL
1
2
3
4
5
6
7
8
9
10
126 130 134 138 140 142 182 228 296 310
140 146 150 170 180 200 224 244 272 280
HEAT
Difference in capacity
Difference in operation number
Code3,4 Code5,6 Code7,8 Code9,10 Code11,12 Code13,14 Code15or above
2
-20
0
3
-30
0
COOL
HEAT
3
3
6
6
9
9
12
52
15
55
25
65
35
75
25
1
MXZ-2A20NA-
Exclusive LEV
Standard opening (pulse)
LEV Opening (code)
COOL
1
2
3
4
5
6
7
8
9
10
120 130 136 146 156 160 170 180 190 200
248 248 258 266 274 280 286 292 300 306
HEAT
Difference in capacity
Difference in operation number
Code3,4 Code5,6 Code7,8 Code9,10 Code11,12 Code13,14 Code15or above
2
COOL
HEAT
3
3
6
6
9
9
12
52
15
55
25
65
35
75
-20
30
Receiver LEV
Standard opening (pulse)
LEV Opening (code)
COOL
1
2
3
4
5
6
7
8
9
10
140 150 160 170 180 190 200 200 200 200
80 84 90 110 120 130 140 150 160 170
HEAT
Difference in operation number
Operation number
2
COOL
HEAT
-20
30
1
MXZ-3A30NA-
MXZ-4A36NA
Exclusive LEV
Standard opening (pulse)
LEV Opening (code)
COOL
1
2
3
4
5
6
7
8
9
10
126 130 134 138 150 160 170 180 190 200
248 248 258 266 274 280 286 292 300 306
HEAT
Difference in capacity
Difference in operation number
Code3,4 Code5,6 Code7,8 Code9,10 Code11,12 Code13,14 Code15or above
2
-20
-4
3
-30
-8
4(MXZ-4A)
-30
-12
COOL
HEAT
3
3
6
6
9
9
12
52
15
55
25
65
35
75
Receiver LEV
Standard opening (pulse)
LEV Opening (code)
COOL
1
2
3
4
5
6
7
8
9
10
270 280 290 300 310 320 330 340 350 360
140 152 160 170 180 200 224 244 274 280
HEAT
Difference in operation number
Operation number
2
28
-45
3
56
-60
4(MXZ-4A)
84
COOL
HEAT
-60
Capacity code
Indoor unit
4
7
9
10 12
09 12 15 17 24
26
<Correction>
COOL
DRY
HEAT
Discharge temperature
2
2
●
●
●
Each correction
• (Each gas pipe temperature thermistor - Minimum gas pipe temperature thermistor)
1
—
●
●
• (Main indoor coil thermistor - Sub indoor coil thermistor)
1 Perform this, when number of operation units is 2 units or more.
1
1
MXZ-2A20NA-
MXZ-3A30NA-
and MXZ-4A36NA are excluded.
,
2 Correct the LEV opening by discharge temperature.
(1) LEV opening correction by discharge temperature
The target discharge temperature is determined according to frequency zone and number of operation unit of the com-
pressor.
MXZ-2A20NA
Target discharge temperature (°F)
Number of operating unit
Operation frequency
of compressor (Hz)
COOL
COOL
COOL
HEAT
HEAT
HEAT
1 unit
95
104
120.2
136.4
149
2 units
136.4
140
1 unit
122
132.8
140
2 units
122
122
132.8
140
140
Minimum ~ 23
24 ~ 38
39 ~ 54
55 ~ 69
70 ~ 85
149
154.4
158
140
140
86 ~ Maximum
158
158
140
140
MXZ-2A20NA-
1
Target discharge temperature (°F)
Number of operating unit
Operation frequency
of compressor (Hz)
1 unit
95
104
120.2
136.4
149
2 units
136.4
140
1 unit
122
132.8
140
2 units
122
122
132.8
140
140
Minimum ~ 23
24 ~ 38
39 ~ 54
55 ~ 69
70 ~ 85
149
154.4
158
158
145.4
150.8
152.6
86 ~ Maximum
158
140
MXZ-3A30NA
Target discharge temperature (°F)
Number of operating unit
Operation frequency
of compressor (Hz)
1 unit
95
104
120.2
136.4
149
154.4
158
2 units
131
131
136.4
140
149
154.4
158
163.4
167
3 units
134.6
134.6
145.4
149
158
163.4
167
1 unit
125.6
136.4
149
154.4
154.4
154.4
154.4
154.4
154.4
172.4
2 unit
143.6
150.8
165.2
172.4
172.4
172.4
172.4
172.4
172.4
172.4
3 units
122
131
Minimum ~ 14
15 ~ 23
24 ~ 32
33 ~ 41
42 ~ 50
51 ~ 59
60 ~ 68
69 ~ 77
78 ~ 86
140
152.6
161.6
168.8
168.8
168.8
168.8
168.8
167
167
167
176
179.6
179.6
87 ~ Maximum
176
27
MXZ-3A30NA-
MXZ-4A36NA
1
Target discharge temperature (°F)
COOL
HEAT
Operation frequency
of compressor (Hz)
Number of operating unit
4 units
4 units
(MXZ-4A36)
1 unit
2 units
3 units
1 unit
2 unit
3 units
(MXZ-4A36)
140
Minimum ~ 14
15 ~ 23
95
131
131
136.4
140
149
154.4
158
163.4
167
176
134.6
134.6
145.4
149
158
163.4
167
176
179.6
179.6
125.6
136.4
149
143.6
150.8
165.2
172.4
172.4
172.4
172.4
172.4
172.4
172.4
122
131
140
152.6
161.6
168.8
168.8
168.8
168.8
168.8
122
122
122
122
131
140
140
140
140
140
107.6
120.2
136.4
149
154.4
158
167
167
167
140
140
24 ~ 32
33 ~ 41
42 ~ 50
51 ~ 59
60 ~ 68
69 ~ 77
78 ~ 86
143.6
149
158
154.4
154.4
154.4
154.4
154.4
154.4
172.4
158
161.6
161.6
161.6
87 ~ Maximum
Correct the LEV opening according to the difference between target discharge temperature and discharge temperature.
MXZ-2A
LEV opening correction (pulse)
Discharge temperature (°F)
More than Target discharge temperature+18
Target discharge temperature + 18 to Target discharge temperature + 9
Target discharge temperature + 9 to Target discharge temperature + 3.6
Target discharge temperature + 3.6 to Target discharge temperature - 3.6
Target discharge temperature - 3.6 to Target discharge temperature - 9
Target discharge temperature - 9 to Target discharge temperature - 18
Target discharge temperature - 18 or less
COOL
HEAT
5
4
8
3
2
1
0
0
-1
-3
-4
-1
-2
-3
MXZ-3A MXZ-4A
LEV opening correction (pulse)
Discharge temperature (°F)
COOL
HEAT
More than Target discharge temperature + 21.6
4
2
1
6
2
1
Target discharge temperature + 21.6 to Target discharge temperature + 9
Target discharge temperature + 9 to Target discharge temperature + 5.4
Target discharge temperature + 5.4 to Target discharge temperature - 5.4
Target discharge temperature - 5.4 to Target discharge temperature - 9
Target discharge temperature - 9 to Target discharge temperature - 21.6
Target discharge temperature - 21.6 or less
0
0
-1
-3
-8
-1
-2
-8
(2) Separate correction (COOL,DRY)
(Correction by the separate super heat)
a) Correct the LEV separately by temperature difference between each gas pipe temperature and the minimum gas pipe
temperature of all.
Calculate each super heat of the unit from the expression below;
(Super heat) = (Each gas pipe temperature) - (Minimum gas pipe temperature)
Separate correction is performed according to each super heat in the table below.
MXZ-2A20NA
MXZ-3A30NA
LEV opening
correction (pulse)
LEV opening
correction (pulse)
Superheat
Superheat
more than 16.2
10.8 to 16.2
5.4 to 10.8
3
2
1
0
more than 16.2
10.8 to 16.2
5.4 to 10.8
12
8
4
5.4 or less
5.4 or less
0
28
b) Correct the LEV separately by temperature difference “ ∆RT” between main/sub indoor coil thermistor.
LEV opening
∆RT
correction (pulse)
10.8 ∆RT
7.2 ∆RT < 10.8
∆RT < 7.2
2
1
1
In addition, decrease the target discharge temperature corresponding ∆RT.
Temperature to be
decreased (°F)
∆ RT
10.8 ∆RT
7.2 ∆RT< 10.8
∆RT < 7.2
18
9
9
3-3. OPERATIONAL FREQUENCY RANGE
MXZ-2A20NA
COOL (Hz)
HEAT (Hz)
Max.
92
Number of operating
unit
Capacity code
DRY (Hz)
Min.
20
20
20
20
30
30
30
20
Max.
65
85
100
100
105
105
105
105
Min.
48
48
48
48
58
58
58
58
Defrost
92
92
100
100
100
100
100
100
4
7
9,10
12
8 ~ 10
11 ~ 13
14 ~ 16
17 ~
25
30
75
75
52
52
52
100
92
100
100
112
112
112
112
1
2
1
MXZ-2A20NA-
COOL (Hz)
HEAT (Hz)
Max.
92
Number of operating
unit
Capacity code
DRY (Hz)
Min.
20
20
20
20
30
30
30
30
Max.
65
85
93
93
93
93
93
93
Min.
48
48
48
48
58
58
58
58
Defrost
92
92
92
92
101
101
101
101
4
7
9,10
12
8 ~ 10
11 ~ 13
14 ~ 16
17 ~
35
34
75
75
52
52
52
93
92
92
92
110
110
110
110
1
2
MXZ-3A30NA
COOL (Hz)
HEAT (Hz)
Number of operating
unit
Capacity code
DRY (Hz)
Min.
15
15
15
15
24
24
24
24
52
Max.
58
58
62
68
80
80
80
80
90
Min.
22
22
22
22
35
35
35
35
39
Max.
48
48
62
90
70
90
94
94
94
Defrost
48
48
58
58
58
58
58
58
4
7
9,10
12
8 ~ 10
11 ~ 13
14 ~ 16
17 ~
12 ~
20
25
44
44
31
31
31
59
65
1
2
3
58
29
1
MXZ-3A30NA-
MXZ-4A
COOL (Hz)
Min.
HEAT (Hz)
Max.
70
Number of operating
unit
Capacity code
DRY (Hz)
Max.
58
58
71
80
80
80
80
80
80
90
90
Min.
20
20
20
20
20
20
20
20
20
20
20
Defrost
58
58
58
58
58
58
58
58
4
7
9,10
12
8 ~ 10
11 ~ 13
14 ~ 16
17 ~
12 ~
12 ~
16 ~
25
25
25
25
25
25
25
25
25
25
25
25
25
25
35
31
31
42
42
52
52
52
70
80
80
80
80
80
80
80
1
2
3 (MXZ-3A)
3 (MXZ-4A)
4 (MXZ-4A)
58
58
58
103
113
3-4. HEAT DEFROSTING CONTROL
(1) Starting conditions of defrosting
When the following conditions a) ~ c) are satisfied, the defrosting starts.
a) The defrost thermistor reads 26.6 °F or less.
b) The cumulative operation time of the compressor has reached any of the set values (31, 35, 45, 55, 65, 75, 85, 95,
105, 115, 150 minutes).
c) More than 5 minutes have passed since the start-up of the compressor.
Set value of compressor operation time (hereinafter referred to as defrost interval)
This is decided by the temperature of defrost thermistor and ambient temperature thermistor, the previous defrosting
time. For example, the first defrost interval is 40 minutes long, and the second is 45 minutes long. The third and sub-
sequent intervals are set to be longer, and less frequent, depending on defrosting time.
…
The third and subsequent defrost intervals follow any of the three patterns 5 or 10 to 20 minutes longer, the same,
…
or 5 or 10 to 20 minutes shorter compared with the previous defrost interval
shortest 40 minutes.
with the longest 125 minutes and the
(2) Releasing conditions of defrosting
Defrosting is released when any of the following conditions is satisfied:
a) The defrost thermistor continues to read 50.7 °F.
b) Defrosting time exceeds 10 minutes.
c) Any other mode than HEAT mode is set during defrosting.
3-5. DISCHARGE TEMPERATURE PROTECTION CONTROL
This protection controls the compressor ON/OFF and operation frequency according to temperature of the discharge tempera-
ture thermistor.
(1) Compressor ON/OFF
When temperature of the discharge temperature thermistor exceeds 240.8 °F, the control stops the compressor.
When temperature of the discharge temperature thermistor is 176 °F (2A/3A30NA)/ 212 °F (3A30NA- 1 /4A) or less, the
controls starts the compressor.
(2) Compressor operation frequency
When temperature of the discharge temperature thermistor is expected to be higher than 240.8 °F, the control decreases
12 Hz from the current frequency.
When temperature of the discharge temperature thermistor is expected to be higher than 231.8 °F and less than 240.8 °F,
the control decreases 6 Hz from the current frequency.
When temperature of the discharge temperature thermistor is expected to be higher than 219.2 °F and less than 231.8 °F,
the control is set at the current frequency.
3-6. OUTDOOR FAN CONTROL
Fan speed is switched according to the number of operating indoor unit and the compressor frequency.
<Relation between compressor frequency and fan speed>
Fan speed
Compressor frequency (Hz)
Down
Up
High
Down
Up
MXZ-2A
MXZ-3A30NA
30
40
Low
1
MXZ-3A30NA-
MXZ-4A
Min. Compressor frequency Max.
40
50
NOTE : When the indoor coil thermistor is 134.6 ˚F or more on HEAT operation, fan speed is fixed to Low speed.
Or, the indoor coil thermistor is 113 ˚F or less on HEAT operation, fan speed is back to normal.
30
3-7. PRE-HEAT CONTROL
MXZ-2A20NA- MXZ-3A30NA-
1
1
MXZ-4A36NA
The compressor is energized even while it is not operating.
This is to generate heat at the winding to improve the compressor's start-up condition.
Power
ON
OFF
Compressor ON
OFF
Outside temperature
68 °F
30min.
30 min.
30 min.
30 min.
30 min.
30 min. 15 min. 30 min.15 min. 30 min.
Pre-heat
ON
OFF
Start
Stop
When outside
temperature is
above 68 °F
Breaker ON
operation operation
1. Pre-heat control is turned ON for 15 or 30 min, after the breaker is turned ON.
2. 30 min. after the unit is stopped, pre-heat control is turned ON for 15 or 30 min. and turned OFF for 30 min."
This is repeated as shown in the graph until the breaker is turned OFF.
When outside temperature is 68 °F or below, pre-heat control is ON for 30 min."
When outside temperature is 69.8 °F or above, pre-heat control is ON for 15 min."
NOTE: When the unit is started with the remote controller, pre-heat control is turned OFF."
Compressor uses 50 W when pre-heat control is turned ON.
3-8. COOL OPERATION
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Thermostat
ON
OFF
-1.8 °F or more
less than-1.8 °F
-1.8 °F
-1.3 °F
2. Coil frost prevention
The compressor operational frequency is controlled to prevent the indoor heat exchanger temperature from falling exces-
sively.
Compressor is turned OFF for 5 minutes when temperature of indoor coil thermistor continues 37.4 °F or less for 5 min-
utes or more.
31
3-9. DRY OPERATION
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Thermostat
ON
OFF
-1.8 °F or more
less than-1.8 °F
-1.8 °F
-1.3 °F
2. Coil frost prevention
Coil frost prevention is as same as COOL mode. (3-8.2.)
3-10. HEAT OPERATION
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Thermostat
ON
OFF
less than 3.6 °F
3.6 °F or more
3.6 °F
3 °F
2. High pressure protection
In HEAT operation the indoor coil thermistor detects the temperature of the indoor heat exchanger. The compressor opera-
tional frequency is controlled to prevent the condensing pressure from increasing excessively.
HEAD OFFICE: TOKYO BLDG.,2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN
Copyright 2006 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Distributed in Feb. 2008. No. OBT16 REVISED EDITION-B 6
Distributed in May 2007. No. OBT16 REVISED EDITION-A 7
Distributed in Apr. 2006. No. OBT16 7
Made in Japan
New publication, effective Feb. 2008
Specifications subject to change without notice.
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