Mitsubishi Heavy Industries SRK25QA-S User manual

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Mitsubishi Heavy Industries Air Conditioners
Technical Manual
Manual Number: 2011 No. W1-01
Variable Frequency Wall Mounted Type
Room Air Conditioners
(Split system, heat pump type)
SRK25QA-S/SRC25QA-S
SRK35QA-S/SRC35QA-S
(R410A Refrigerant Used)
MITSUBISHI HEAVY INDUSTRIES, LTD.

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Table of Contents
1. GENERAL INFORMATION……..…………………………….……1
1.1 Features…………………………………………………………..…1
1.2 Model identification………………………………………………1
2 MODEL SELECTION…………………………………………………2
2.1 Model function..…………..…….……..………………………..……2
2.2 Range of usage……………………………………………..………4
2.3 Outline drawing…..………………………………………………..…4
2.4 Cooling cycle system diagram….…………………..…………...…5
2.5 Performance curve……………………………………………………6
3 ELECTRICAL WIRING DIAGRAM………………………………….7
4 NAME OF EACH PARTAND ITS FUNCTION……………….….….9
4.1 NAME OF EACH PART………………..………….………………9
4.2 Emergency “ON/OFF” button (back-up switch) …........………..12
4.3 Automatic restart……………..…………..………………………..12
4.4 Flap control………..…………..……..……………………………..12
4.5 Comfort timer setting……..……..……..…………………………..14
4.6 Outline of heating operation.……..………………………….……..15
4.7 Outline of cooling operation ............................................................ 17
4.8 Outline of drying operation ................................................. 18
4.9 Outline of automatic operation ..........................................................20
4.10 Economical operation.....................................................................20
4.11 Air blowing operation.......................................................................20
4.12 CLEAN operation control...................................................21
4.13 EEV control.....................................................................................21
5 INSTALLATION................................................................................22
5.1 Selection of installation location.................................................24
5.2 Installation of indoor unit..................................................................25
5.3 Installation of outdoor unit...............................................................28

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5.4 Pipe connection.................................................................................28
5.5 Precautions for wireless remote controller operation........................30
5.6 Standard running data........................................................................31
6 MAINTENANCE................................................................................32
6.1 Electrical parts failure diagnosis method............................................32
6.2 Servicing.............................................................................................56
7 SERVICING MANUAL.......................................................................57
8MOUNT ASSEMBLY………………………….................................72
8.1 Indoor unit.........................................................................................72
8.2 Outdoor unit......................................................................................80

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1 GENERALINFORMATION
1.1 Features
(1) Inverter
● Heating/cooling
The rotate speed of the compressor is changed steplessly in relation to varying load, and is
linked with the fans of indoor and outdoor units controlled by the changes of frequency, thus
controls the power.
● Allowing quick heating/cooling operation during start-up period.
The room temperature is kept constant through fine-tuned control after the machine is
stabilized.
(2) Fuzzy control: According to the fuzzy control technology, the room temperature and humidity,
etc. are obtained through dynamic analysis to accurately regulate the rotate
speeds of the compressor and the fan to realize precise temperature control.
(3) Life: Actual service life: over 20,000 hours; Working life: over 100,000 hours; On/off of relay:
over 100,000 times; Continuous on of LED: over 50,000 hours; On/off of emergency
switch: over 10,000 times.
(4) Self diagnosis function: We will continuously provide the best services for our customers
through devices judging abnormal operation, as follows:
The air conditioner indicates the error of the indoor and outdoor sensors (thermistors) only when
it is in the stop mode. Error indication is removed after restart.
1.2 Model identification
R410A Refrigerant used
Master pattern change code
Master pattern
Capacity
Wall mounted type (C is the code for outdoor unit.)
Split type room air conditioner
TIMER lamp
ON
RUN lamp
keeps flashing
RUN lamp
ON
RUN lamp
Flash 2 times
RUN lamp
Flash 1 time
Flash 2 times
Flash 5 times
Flash 6 times
TIMER lamp
Flash 1 time
Flash 2 times
Flash 4 times
Flash 1 time
Flash 2 times
Flash 3 times
Flash 4 times
Flash 5 times
Flash 6 times
Flash 2 times
Failure Causes
Heat exchanger sensor error
Room temperature sensor error
Abnormal voltage input
Indoor fan motor error
Outdoor unit temperature sensor
error
Outdoor unit heat exchanger liquid
pipe sensor error
Vent-pipe sensor error
Current cut
Outdoor unit error
Safe current
Power transistor error
Compressor over heat protection
Signal transmission error
Rotor lock
Heat exchanger sensor wire break, poor connector connection
Room temperature sensor wire break, poor connector connection
Voltage too high or too low
Failure of fan motor, poor connector connection
Outdoor unit sensor wire break, poor connector connection
Heat exchanger liquid pipe sensor wire break, poor connector
connection
Vent-pipe sensor wire break, poor connector connection
Compressor blockage, compressor output open-phase, power short
circuit, control valve closed
Power-cut, compressor wire break
Vent-pipe sensor wire break, poor connector connection
Compressor not rotating (dead lock)
Overload, over current
Failure of power transistor
Insufficient refrigerant, failure of vent-pipe sensor, control valve
closed
Failure of power supply, signal cable break, failure of
indoor/outdoor unit control device
Failure of compressor
Compressor open-phase
Failure of outdoor unit control device

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2 MODEL SELECTION
2.1 Model function
2.1.1 Model: SRK25QA–S (Indoor unit)
SRC25QA–S (Outdoor unit)
Item
Unit
Indoor unit SRK25QA–S
Outdoor unit SRC25QA–S
Net weight
kg
9
31
Machine
dimension
mm
790×222×268
780×290×540
Package
dimension
Length× Width
×Height
830×340×280
920×380×590
Color
White
Ash-colored
Fan
Through-flow type, AS resin + glass
fiber
Axial flow type, AS resin + glass
fiber
Air flow
m3/h
550
1830
Noise in cool
room
dB(A)
Hi/Me/Lo:
37/30/23(completely mute,
SPL)
45(completely mute, SPL)
Noise in warm
room
dB(A)
Hi/Me/Lo:
37/32/28(completely mute,
SPL)
48(completely mute, SPL)
Fan motor
Nominal value
16W, 4-step capacitor type
asynchronous motor, insulation
grade E
25W, AC motor, insulation grade B
Power of motor
W (reference
value)
40
50
Power of electric
control
W (reference
value)
2
7.5
Power supply and
power cord
Single-phase, 220V, 50Hz and 3-core, 1.0mm2, 250V, 10A, 2m, w/o plug
Heat exchanger
Spiral, hydrophilic, 3-folded,
16-section, 2-row, 452-fin, 1-2
circuit
Spiral, hydrophilic, 20-section,
1-row, 621-fin, 2-1 circuit
Compressor
Nominal value
THACOM RM - B5077MDE2, 527W, DC frequency conversion
compressor, insulation grade E
Refrigerating
machine oil
ml
300, DIAMOND FREEZE MA68
Refrigerant
controller
Electronic expansion valve (Φ1.65mm) + hush pipe
Refrigerant
g
R-410A, 850g, addition/reduction not needed within the use range of 15m
Operating
pressure limit
Mpa
Max.: 4.1, Min.: 1.47
Air filter
Mould-proof air filter
Accessories and
quantity
Indoor unit 1, mounting plate 1, tapping screw 5, battery 2, use and
installation manual 1, remote controller 1, outdoor unit 1, Drain elbow 1,
Water shutoff plug 1
Operation control
devices
Wireless remote controller, electronic thermostat controlling room
temperature, microcomputer controlling defrosting
Safety devices
Serial signal protection, fan error protection, compressor over heat
protection, high voltage protection, over current protection, etc.
* The nominal values of “Noise in cool room” and “Noise in warm room” in the above table are tested in a dead
room.
Item
Unit
Rating cooling
Rating heating
Capacity
W
2500
3200
Power
W
700
870
Energy efficiency ratio
3.57
3.68
Energy efficiency grade
Grade A (European norm)
Note (1) The data are measured at the following conditions. The pipe length is 5m.
Item
Operation
Indoor air temperature
Outdoor air temperature
Standards
DB
WB
DB
WB
Cooling
27℃
19℃
35℃
24℃
Heating
20℃
—
7℃
6℃
Low temperature Heating
20℃
—
2℃
1℃
(2) The operation data are applied to the 220Vdistricts respectively.
(3) The refrigerant quantity to be charged includes the refrigerant in 15m connecting piping.
(Purging is not required even for the short piping.)

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2.1.2 Model: SRK35QA–S (Indoor unit)
SRC35QA–S (Outdoor unit)
Item
Unit
Indoor unit SRK35QA–S
Outdoor unit SRC35QA–S
Net weight
kg
9.5
35
Machine
dimension
mm
790×222×268
780×290×540
Package
dimension
Length× Width
×Height
830×340×280
920×380×590
Color
White
Ash-colored
Fan
Through-flow type, AS resin + glass
fiber
Axial flow type, AS resin + glass
fiber (embedded damping spindle
sleeve)
Air flow
m3/h
520
1940
Noise in cool
room
dB(A)
Hi/Me/Lo: 40/33/25
47
Noise in warm
room
dB(A)
Hi/Me/Lo: 39/35/27
48
Fan motor
Nominal value
16W, 4-step capacitor type
asynchronous motor, insulation
grade E
24W, DC motor, insulation grade E
Power of motor
W (reference
value)
40
20
Power of electric
control
W (reference
value)
2
7.5
Power supply and
power cord
Single-phase, 220V, 50Hz and 3-core, 1.0mm2, 250V, 10A, 2m, w/o plug
Heat exchanger
Spiral, hydrophilic, 3-folded,
16-section, 2-row, 452-fin, 1-4
circuit
Child heat exchanger: Spiral,
hydrophilic, 1-row, 4-section,
408-fin
Spiral, hydrophilic, 20-section,
2-row, 1221-fin, 2-1 circuit
Pf1.4
Compressor
Nominal value
THACOM RM - B5077MDE2, 527W, DC frequency conversion
compressor, insulation grade E
Refrigerating
machine oil
ml
300, DIAMOND FREEZE MA68
Refrigerant
controller
Electronic expansion valve (Φ1.5mm) + hush pipe
Refrigerant
g
R-410A, 900g, addition/reduction not needed within the use range of 15m
Operating
pressure limit
MPa
Max.: 4.15, Min.: 1.47
Air filter
Mould-proof air filter
Accessories and
quantity
Indoor unit 1, mounting plate 1, tapping screw 5, battery 2, use and
installation manual 1, remote controller 1, outdoor unit 1, Drain elbow 1,
Water shutoff plug 1
Operation control
devices
Wireless remote controller, electronic thermostat controlling room
temperature, microcomputer controlling defrosting
Safety devices
Serial signal protection, fan error protection, compressor over heat
protection, high voltage protection, over current protection, etc.
* The nominal values of “Noise in cool room” and “Noise in warm room” in the above table are tested in a dead
room.
Item
Unit
Rating cooling
Rating heating
Capacity
W
3500
4000
Power
W
1020
1100
Energy efficiency ratio
3.43
3.64
Energy efficiency grade
Grade A (European norm)
Note (1) The data are measured at the following conditions. The pipe length is 5m.
Item
Operation
Indoor air temperature
Outdoor air temperature
Standards
DB
WB
DB
WB
Cooling
27℃
19℃
35℃
24℃
Heating
20℃
—
7℃
6℃
Low temperature Heating
20℃
—
2℃
1℃
(2) The operation data are applied to the 220Vdistricts respectively.
(3) The refrigerant quantity to be charged includes the refrigerant in 15m connecting piping.

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(Purging is not required even for the short piping.)
2.2 Range of usage
Please use the air conditioners within the following range of usage, otherwise the protector will be
triggered.
Cooling Operation
Heating Operation
Outdoor temperature
About 18℃~43℃
About -15~24℃
Room temperature
About18℃~32℃
About below 30℃
Indoor humidity
About below 80%
25~35 Models
Max. piping one-way length
Within 15 m
Vertical height difference
Within 5 m
Additional R410A Refrigerant
Not required
Voltage
Rating ±10%
Starting voltage
At least 85% of rating
Switching frequency
Max. 10 times per hour
Time interval between stop and start
Min. 3 min
2.3 Outline drawing
(1) Indoor unit: SRK25QA–S/ SRK35QA–S Unit: mm
Piping hole right (left)
Terminal block
Remote controller
Flare connecting (Gas)
Flare connecting (Liquid)
Drainage pipe
Piping hole
Piping hole
VIEWA

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(2) Outdoor unit: SRC25QA-S/ SRC35QA-S Unit: mm
2.4 Cooling cycle system diagram
Models: QA-S Series
Note (1)……line is piping for site construction.
Drain holes
Terminal block
Flare connecting
Flare connecting
Operation valve (Gas)
Operation
valve
(Liquid)
Indoor unit
Outdoor unit
Circulation of cooling
Circulation of heating
Flare connecting
Operation valve (Gas)
Outdoor air
temp. sensor
Air heat
exchanger
Heat exchanger
sensor
Gas liquid
separator
Compressor
Discharge pipe sensor
4-way valve
Check joint
Gas pipeNote (1)
model
Air heat
exchanger
Inlet air temp.
sensor
Air heat
exchanger sensor
Liquid pipe
Flare connecting
Filter
Electronic expansion valve
Hush pipe
Hush pipe
Operation valve (Liquid)
Refrigerant inlet pipe
Refrigerant outlet
pipe

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2.5 Performance curve
The cooling and heating capacities are measured in the following conditions. The actual capacity
can be obtained with the following formula.
Actual capacity = Rating capacity x Correction factor
(1) Capacity correction according to indoor and outdoor temperatures:
Outdoor air W.B. temperature (°C W.B.) ISO-T1 Standard
⑵Capacity correction according to one way length of refrigerant piping:
It is necessary to correct the cooling and heating capacity according to the one way length of
refrigerant piping.
Piping length (m)
7
10
15
Cooling
1.0
0.99
0.975
Heating
1.0
1.0
1.0
⑶Capacity correction according to frosting on outdoor heat exchanger during heating:
In additions to the foregoing corrections (1) and (2), the heating capacity also needs to be
corrected according to the frosting on the outdoor heat exchanger.
Air inlet temperature of
outdoor unit
-10
-9
-7
-5
-3
-1
1
3
5
Frosting correction factor
0.95
0.94
0.93
0.91
0.88
0.86
0.87
0.92
1.00
⑷Example of cooling and heating capacity calculation:
The actual cooling capacity of model SRK25QA-S with the one way piping length of 25m at the
indoor wet-bulb temperature of 19℃and outdoor dry-bulb temperature of 35℃in summer or
indoor dry-bulb temperature of 20℃, outdoor dry-bulb temperature of 1℃and indoor wet-bulb
temperature of -1℃in winter is
Actual cooling capacity = 2500 x 1.0 x 0.95 ≈ 2375W
Nominal cooling Temp. correction Piping length
capacity factor correction factor
Actual heating capacity = 3200 x 0.81 x 0.95 x 0.86 ≈2118W
Nominal heating Temp. correction Piping length Frosting
capacity factor correction factor correction factor
Cooling
Heating
Accommodation
Cooling operation
Heating operation
Indoor air D.B.
temperature
Outdoor air D.B.
temperature
Indoor air W.B. temperature (°C W.B.) ISO-T1 Standard
Correction factor of cooling & heating
capacity in relation to temperature

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3 ELECTRICALWIRING DIAGRAM
3.1 Circuit diagram: 25QA-S

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3.2 Circuit diagram: 35QA-S

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4 NAME OF EACH PARTAND ITS FUNCTION
4.1 Name of each part
Indoor unit
Air inlet panel
Draws in the indoor air.
Unit indication section and remote control signal receiver
Wireless remote control
Air filter
filtere
Removes dust or dirt from the inlet air
Room temperature detector
filtere
Unit operation switch
filtere
Air blows from here.
Up/down air direction flap
Page 11
Drain hose
Drains water from the dehumidified air.
Refrigerant piping connection electric flex
Outdoor unit
Accessories
Air inlet
Air out
(on side&rear suface)
Battery
Wireless remote controller
Air outlet

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Indication section of air conditioner
RUN lamp (green)
ON during running and
mould-proof running
TIMER lamp (yellow)
ON during timing operation
HI POWER lamp (green)
ON during Hi Power running
Opening the air inlet grille
Put your hands on the indentations on both sides, raise the grille towards yourself, and stop at the
opening position of about 60°.
Closing the air inlet grille
Gently push both sides and then gently push the central portion.
Removing and mounting the air inlet grille
To remove the air inlet grille to clean the inside,
open it at the position of about 65°and pull it
towards yourself to remove the grille.
To mount the air inlet grille, insert the mounting
arm in the pin roll on the main frame and close the
grille.
ECONO lamp (green)
ON during ECONO running

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Operation and indication section for remote control
Operation section
FAN SPEED button
Each time the button is pushed ■indicator is
switched over in turn.
HI POWER/ECONOMY button
TEMPERATURE button
This button sets the room tem-
perature.(press the button to select the
current time and timing time)
ON TIMER button
This button sets the ON timer Times.
CLEAN button
Indication section
SLEEP indicator
Indicates during SLEEP mode
operation.
TEMPERATURE indicator
FAN SPEED indicator
Indicates set air flow rate with■lamp.
lamp.
HI POWER/ECONOMY indicator
Display in the HI POWER/ ECONOMY operation mode respectively.
OPERATION MODE select button
Each time the button is pushed ■
indicator is switched over in turn.
ON/OFF button
Press for starting operation pr-
ess again for stopping.
AIR FLOW button
This button sets the swaying
way of the air flap.
OFF TIMER button
CANCEL button
The button is used to cancel the timing
ONtimer/OFF timer and SLEEP operation.
ON /OFF TIMER indicator
Indicates during ON/OFF TIMER mode operation.
mode operation.
Operation mode indicator
Indicates selected operation with lamp.
Time display lamp
Display the current time or the time
set by timer.
■is used to indicate the mode selected: [ (AUTO)
(COOLING) (HEATING) (DRYING)]
Display the swaying way of the wind guide blade.
The above illustration shows all
controls,but in practice only the
relevant parts are shown.
CLEAN indicator
ON/OFF (luminous) button
This button changes the HI PO-
WER /ECONOMY mode.
SLEEP button
This button changes the
“SLEEP” mode.
This button changes the “CLEAN” mode.
RESET switch
Switch for resetting microcomputer.
This button sets the OFF timer
Times.
Indicates set temperature.
(Does not indicate temperature
when operation mode is on AUTO)
Air supply display lamp

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4.2 Emergency “ON/OFF” button (back-up switch)
When the battery of the remote controller runs out or the remote controller is lost or
malfunctioning, this switch can be used to turn the unit on and off.
(1) Operation method
Press the switch once to place the unit in the AUTO mode. Push it once more to turn the unit off.
(2) Detail of operation
The system operates in the COOL, DRY or HEAT mode according to the room temperature
(temperature at the temperature detection point).
Note: To repair or move the machine, push and hold the switch for more than 5 seconds to set to
the cooling mode automatically.
Function
Operating mode
Set temperature
Fan speed
Flap
Timer
conversion
COOL
About 24℃
Automatic
Automatic
Continuous
DRY
About 24℃
HEAT
About 26℃
Emergency “ON/OFF” button on the equipment
4.3 Automatic restart due to power cut:
(1) This function can rapidly record the operation state immediately before the air conditioner is
switched off due to power failure, and will resume operation automatically after the power
supply is restored.
(2) This function is set to Active by default.
(3) Operation state memorized immediately before power cut includes:
● Indoor operation switching (cool room · warm room · drying · automatic · air flow, stop)
● Air flow
● Power Save
● Set temperature
● Air direction
(4)After automatic restart due to power cut, the following settings will be canceled:
Timing operation, HI POWER operation, CLEAN operation
(5) Priority of start:
Compressor 3 min. delayed start control >Automatic restart due to power cut
4.4 Flap control
(1) Swing of vertical flap (SM1)
The vertical flap continuously swings upward and downward.
Set the angle and pulse count (0° for horizontal)
①
②
③
④
⑤
⑥
⑦
⑧
SM1
Angle
75°
70°
65°
60°
55°
50°
45°
40°
Pulse count
0
57
114
171
228
284
341
398
⑨
⑩
SM1
Angle
32°
30°
25°
20°
15°
10°
5°
-24°
Pulse count
489
512
569
626
683
739
796
1274
Note: Max control range: 1274 pulse.
(2) Non-operating period
When the machine stops, the vertical flap fully closes.

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(3) Flap memorizing function (where the vertical or horizontal flap stops)
When you press the AIR FLOW (Up/Down or Left/Right) button, the flap will operate at the
angle set. As this angle is memorized in the microcomputer, the flap will automatically operate
at the same angle next time the machine is started.
● Recommended angle of flap
(4) Flap control
The flap is controlled with the FLAP button on the remote controller.
(a) Automatic direction
The flap is automatically set to the best air flow angle in an operating mode.
1) Start time of operation
COOL and DRY operation HEAT operation
The flap moves repeatedly as The flap moves repeatedly as
shown in the above figure. shown in the above figure.
● In the HEAT mode, when the climator
(thermostat) functions or the DRY
operation is in progress, it becomes
horizontal automatically.
2) Non-operating period
When the machine stops, the flap fully closes.
(b) Flap memorizing function
As this angle is memorized in the microcomputer, the flap will automatically operate at the
angle next time the machine is started.
(c) Swing
As shown in the figure below, the flap swings upward/downward and to the left/right
continuously.
HEAT
(Slant forward
blowing)
COOL, DRY
(Horizontal
blowing)
Stops here for 1
minute
Swing
Swing
Stops here for 3
min. and 50 sec.

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4.5 Comfort timer setting
If, in the COOL or HEAT mode or Automatic COOL or HEAT mode, the timer is set to ON, the
Comfort Timer functions.
The initial value is 15 minutes. The start time for next operation is determined according to the
relationship between the room temperature (sensor) at the time of setting and the set temperature
(max. 60 minutes).
Operating
mode
Correction value at the start of operation (minute)
COOL
3 < room temperature -
set temperature
1 < room temperature -
set temperature ≤ 3
room temperature - set
temperature ≤ 1
+5
No change
-5
HEAT
3 < room temperature -
set temperature
2 < room temperature -
set temperature ≤ 3
room temperature - set
temperature ≤ 2
+5
No change
-5
Notes: (1) The room temp. sensor (Th1) commences operation 5 minutes before the timer is ON,
regardless of the temperature.
(2) In the DRY or Automatic DRY mode, the function does not work.
However, in theAutomatic DRY mode, the operation described in (1) commences.
(3) During the comfort reservation operation, the RUN lamp and TIMER lamp light up.
After expiration of the timer, the TIMER lamp goes off.
(Example) HEAT
Detect the temperature difference to compensate the start time of next operation.
15 min 10 min 5 min time set
earlier earlier earlier
● If the difference between the set temperature and room temperature is 4℃, according to the
above table, the correction value is +5 minutes, therefore, the start time of next operation is:
15 minutes earlier + 5 minutes = 20 minutes earlier
Compensation value
Start time of current operation
Set temp,
Room temp.
Time

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4.6 Outline of heating operation
(1) Operation of functional components
Item
Functional
component
Instruction frequency 0
Instruction frequency
other than 0
Changed to a value other
than 0 due to abnormal
stop
Indoor fan motor
ON
ON
OFF
Swinging flap
ON or OFF
ON or OFF
Stop position control
Indication
Light up
Light up
Light up or flash
52C relay
ON
ON
OFF in Stop mode
Outdoor fan motor
Depending on Stop mode
ON
Depending on Stop mode
4-way valve
Depending on Stop mode
ON (Indoor continuous
instructions-1)
Depending on Stop mode
EEV
Depending on EEV
control
(2) Air flow switching
(a) The inverter instruction frequency changes within the range of selected air flow.
Model
Air flow switching
SRK25QA-S
SRK35QA-S
AUTO
Frequency
30-110 rps
30-112 rps
Air flow
Corresponding to frequency
HI
Frequency
30-110 rps
30-112 rps
Air flow
8th speed
ME
Frequency
30-72 rps
30-78 rps
Air flow
5th speed
LO
Frequency
30-42 rps
30-50 rps
Air flow
3rd speed
(b) When the defrosting or protection device is actuated, operation is performed in the
corresponding mode.
(c) Outdoor fan operates in accordance with the instruction frequency.
(3) Details of control in each operating mode
(a) Fuzzy operation
Deviation between the room temperature setting compensation value and the suction air
temperature is calculated in accordance with the fuzzy rule, and used for control of the air
flow and the inverter frequency.
(b) Heating constant temperature operation (HEAT operation)
● Operating conditions
If the frequency obtained with the fuzzy calculation drops below -24 rps during the heating
fuzzy operation, the operation changes to the heating constant temperature operation.
● Detail of operation
Model
Item
SRK25QA-S, SRK35QA-S
Inverter instruction
frequency
0 rps [Comp. stopped]
Indoor fan
Heat-retaining (normal operating mode)→1st speed (OFF)
Outdoor fan
According to the stop mode
Flap
According to the HEAT and DRY flap control
(c) Heat-retaining operation
During the heating operation, the indoor fan is controlled based on the temperature of the
outdoor heat exchanger (measured by indoor heat exchanger sensor) to prevent cool wind
from blowing.
● Normal operation (Usual heating operation, HI POWER operation)
Temp. of indoor heat exchanger (°C)
Note: (1) For the values of A and B, see the above table.
● Values of A, B
A
B
At 0 rps
instruction
22
25
Other than 0
rps
instruction
10
15
Indoor fan
Fan speed

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● Heat-retaining M mode (automatic, economical operation (15 minutes))
Temp. of indoor heat exchanger (°C)
Note: (1) For the values of A and B, see the above table.
● Values of A, B
A
B
At 0 rps
instruction
22
25
Other than 0
rps
instruction
10
15
(d) Defrosting operation
1) Starting conditions (The defrosting operation is started only when all of the
following conditions are met.)
①35 minutes after start of heating operation (accumulated operation time).
②35 minutes after end of defrosting operation (accumulated compressor operation
time).
③The temperature measured by the outdoor heat exchanger liquid pipe sensor (Th4) has
been below –5ºC for 3minutes continuously.
④Temperature measured by outdoor air temp. sensor (Th5) - Temperature measured by
outdoor heat exchanger liquid pipe sensor (Th4) > 5ºC.
⑤During compressor operation. (However, the defrosting can’t operate within 10
minutes after the compressor commences operation.)
In addition, if the count exceeds 10 times when the inverter frequency of the indoor
controller is 0 rps during heating operation, only ①, ②and ③should be satisfied.
(However, the temperature measured by Th4 is below -5°C when the frequency is
above 62 rps and below -4°C when the frequency is below 62 rps.)
2) Operation of functional components during defrosting operation
● 25, 35 models
Note: When the temperature measured by the outdoor heat exchanger sensor (Th4) becomes 2 ºC or higher,
the inverter instruction frequency changes from 70 rps to 50 rps.
3) Ending conditions (Operation returns to the heating operation when either of the
following is met.)
①Temperature measured by outdoor heat exchanger sensor (Th4): 13ºC or higher
②Continued operation time of defrosting: More than 10 min.
Indoor fan
Fan speed
Indoor
Corresponding
speed
Heat-retaining
Indoor fan
RUN lamp
Flashing
(Heat-retaining)
Heat-retaining
Outdoor
Fuzzy calculated
value
Inverter
instruction
frequency
Outdoor fan
4-way valve
Corresponding
speed
Defrosting operation
preparation
Defrosting operation
50 sec.
60 sec.
6th
speed
6th
speed
Final defrosting operation
Normal heating operation
Defrosting control
Defrosting end
(Th4≥13C, 10 min

-17-
(e) HI POWER Heating operation (HI POWER button on remote controller: ON)
High rotate speed operation for15 minutes.
● Detail of operation
Model
Item
SRK25QA-S
SRK35QA-S
Inverter instruction frequency
110
112
Indoor fan
Heat-retaining mode (max. 9th speed)
Outdoor fan
Corresponding to instruction frequency
Notes: (1) Room temperature can’t be adjusted during the HI POWER operation.
(2) Priority is given to actuation of protective device even during the HI POWER operation.
4.7 Outline of cooling operation
(1) Operation of functional components
Item
Functional component
Instruction frequency 0
Instruction frequency
other than 0
Becomes 0 due to
abnormal stop
Indoor fan motor
ON
ON
OFF
Swinging flap
ON or OFF
ON or OFF
Stop position control
Indication
Light up
Light up
Light up or flash
52C relay
ON
ON
OFF in Stop mode
Outdoor fan motor
Depending on Stop mode
ON
Depending on Stop mode
4-way valve
Depending on Stop mode
OFF (Indoor continuous
instructions-0)
Depending on Stop mode
EEV
Depending on EEV
control
(2) Air flow switching
(a) The inverter instruction frequency changes within the range of selected air flow.
Model
Air flow switching
SRK25QA-S
SRK35QA-S
AUTO
Frequency
20~92 rps
20~106 rps
Air flow
Corresponding to frequency
HI
Frequency
20~92 rps
20~106 rps
Air flow
6th speed
ME
Frequency
20~55 rps
20~66 rps
Air flow
4th speed
LO
Frequency
20~34 rps
20~38 rps
Air flow
2nd speed
(b) When the protection device is actuated, operation is performed in the corresponding mode.
(c) Outdoor fan operates in accordance with the instruction frequency.
(3) Details of control in each operating mode
(a) Fuzzy operation
Deviation between the room temperature setting compensation value and the suction air
temperature is calculated in accordance with the fuzzy rule, and used for control of the air
flow and the inverter frequency.
(b) Cooling constant temperature operation
●Operating conditions
If the frequency obtained with the fuzzy calculation drops below -24 rps during the
cooling fuzzy operation, the operation changes to the cooling constant temperature
operation.
● Detail of operation
Model
Item
SRK25QA-S, SRK35QA-S
Inverter instruction
frequency
0 rps [Comp. stopped]
Indoor fan
According to the Indoor Fan Operating Mode Table (corresponding to fan speed)
Outdoor fan
Stop