Basic Control
SiUS281117
Function and Control
33
2. Basic Control
2.1
Normal Operation
Cooling
Heating
Heating operation is not functional at an outdoor air temperature of 82
FDB or more.
Parts Name
Symbol
Electric Symbol
Operation
Remarks
RZR18/24/30P
RZQ18/24/30P
RZR36/42P
RZQ36/42P
RZR18/24/30P
RZQ18/24/30P
RZR36/42P
RZQ36/42P
Compressor (INV.)
M1C
M1C
Compressor
PI control
Compressor
PI control
Used for high pressure
protection control, low
pressure protection
control, discharge pipe
temperature protection
control, and compressor
operating frequency upper
limit control with inverter
protection control.
Outdoor unit fan
M1F
M1F
M2F
Cooling fan
control
Cooling fan
control
Four-way valve
20S1
Y1S
Y1S
OFF
OFF
Electronic expansion valve
(Main)
EV1
Y1E
Y1E
1400 pls
480 pls
Electronic expansion valve
(Subcooling)
EV3
Y3E
PI control
Solenoid valve (Hot gas)
SVP
Y2S
Y2S
OFF
OFF
This valve turns ON with
low pressure protection
control.
Solenoid valve (Receiver
gas discharging)
SVG
Y3S
OFF
Parts Name
Symbol
Electric Symbol
Operation
Remarks
RZQ18/24/30P
RZQ36/42P
RZQ18/24/30P
RZQ36/42P
Compressor (INV.)
M1C
M1C
Compressor
PI control
Compressor
PI control
Used for high pressure
protection control, low
pressure protection
control, discharge pipe
temperature protection
control, and compressor
operating frequency upper
limit control with inverter
protection control.
Outdoor unit fan
M1F
M1F
M2F
STEP 8
Step 7 or 8
The fan step changes to
STEP 1 with high pressure
> 454 psi.
Four-way valve
20S1
Y1S
Y1S
ON
ON
Electronic expansion valve
(Main)
EV1
Y1E
Y1E
PI control
PI control
Electronic expansion valve
(Subcooling)
EV3
Y3E
PI control
Solenoid valve (Hot gas)
SVP
Y2S
Y2S
OFF
OFF
This valve turns ON with
low pressure protection
control.
Solenoid valve (Receiver
gas discharging)
SVG
Y3S
OFF