19 Troubleshooting
Installation and operation manual
41
RYYQ+RYMQ+RXYQ8~20U7Y1B
VRV IV+ heat pump
4P546220-1C – 2020.10
Main code
Sub code
Cause
Solution
Master
Slave 1
Slave 2
Low pressure malfunction:
▪ Stop valve closed
▪ Refrigerant shortage
▪ Indoor unit malfunction
▪ Open stop valves.
▪ Check refrigerant recharge
unit.
▪ Check the user interface's display or
transmission wiring between the
outdoor unit and the indoor unit.
Electronic expansion valve malfunction
(main) (Y1E) - A1P (X21A)
Check connection on PCB or actuator.
Electronic expansion valve malfunction
(liquid cooling) (Y3E) - A1P (X23A)
Check connection on PCB or actuator.
Electronic expansion valve malfunction
(subcool) (Y2E) - A1P (X22A)
Check connection on PCB or actuator
Electronic expansion valve malfunction
(storage vessel) (Y4E) - A1P (X25A)
Check connection on PCB or actuator
Discharge temperature too high
(R21T/R22T):
▪ Stop valve closed
▪ Refrigerant shortage
▪ Open stop valves.
▪ Check refrigerant recharge
unit.
Compressor casing temperature too
high (R8T/R9T):
▪ Stop valve closed
▪ Refrigerant shortage
▪ Open stop valves.
▪ Check refrigerant recharge
unit.
▪ Refrigerant overcharge
▪ Stop valve closed
▪ Check refrigerant recharge
unit.
▪ Open stop valves.
Ambient temperature sensor
malfunction (R1T) - A1P (X18A)
Check connection on PCB or actuator.
Discharge temperature sensor
malfunction (R21T): open circuit - A1P
(X19A)
Check connection on PCB or actuator.
Discharge temperature sensor
malfunction (R21T): short circuit - A1P
(X19A)
Check connection on PCB or actuator.
Discharge temperature sensor
malfunction (R22T): open circuit - A1P
(X19A)
Check connection on PCB or actuator.
Discharge temperature sensor
malfunction (R22T): short circuit - A1P
(X19A)
Check connection on PCB or actuator.
Compressor casing temperature
sensor malfunction (R8T): open circuit
- A1P (X19A)
Check connection on PCB or actuator.
Compressor casing temperature
sensor malfunction (R8T): short circuit
- A1P (X19A)
Check connection on PCB or actuator.
Compressor casing temperature
sensor malfunction (R9T): open circuit
- A1P (X19A)
Check connection on PCB or actuator.
Compressor casing temperature
sensor malfunction (R9T): short circuit
- A1P (X19A)
Check connection on PCB or actuator.
Suction temperature sensor
malfunction (R3T) - A1P (X30A)
Check connection on PCB or actuator.
De-icing temperature sensor
malfunction (R7T) - A1P (X30A)
Check connection on PCB or actuator
Liquid temperature sensor (after
subcool HE) malfunction (R5T) - A1P
(X30A)
Check connection on PCB or actuator.
Liquid temperature sensor (coil)
malfunction (R4T) - A1P (X30A)
Check connection on PCB or actuator.
