10 Troubleshooting
Troubleshooting procedure
SMGB0091 rev.2 - 11/2015
234
Alarm code
47
Activation to protect system from excessively low suction pressure
(Protection from vacuum operation)
In the case that the evaporating temperature (Cooling: liquid refrigerant piping temperature of indoor unit; Heating:
evaporating temperature of RASC unit) is lower than -37 ºC (250~350 kΩ) and the thermistor temperature on top of
compressor is higher than 90 ºC for 3 minutes, retry operation is performed 3 minutes after compressor stoppage.
However, when the state occurs more than 3 times including 3 in one hour, this alarm code is indicated.
Is the thermistor THM8 of RASC
unit connected to PCB1?
Connect it
No
Yes
Is the thermistor THM3 of indoor
unit connected to PCB?
No
Repair leaks of gas
Yes
Is resistance of THM3 and THM8
between 0.24kΩ and 500kΩ?
Yes
Is gas leaking?
Yes
Faulty thermistor
Recharge refrigerant
No
No
Connect it
Phenomenon
Cause
Check item
Action
(Turn OFF Main Switch)
– Faulty indoor unit liquid
refrigerant temperature
thermistor
– Faulty RASC unit evaporating
temperature thermistor
Fault
Check resistance.
Replace thermistor if faulty.
Incorrect connection
Check wiring to PCB.
Repair wiring and connections.
Faulty PCB (RASC unit, Indoor unit)
Replace PCB and check the
operation.
Replace PCB if faulty.
Excessively low suction
pressure (in vacuum)
Liquid line stop valve is not
open before operation
Check stop valve.
Fully open stop valve.
Faulty or malfunction of
expansion valve
Check for clogging.
Remove clogging.
Check connecting wiring and
connectors.
Replace connector.
Check operating sound from
coil.
Replace coil.
Check discharge gas thermistor.
Replace thermistor.
Check attaching state of
discharge gas thermistor.
Reattach thermistor.
Refrigerant leakage
Check each temperature and
pressure.
Charge refrigerant after
vacuum pumping.
Check gas leakage part.
Correctly charge refrigerant
after repairing gas leakage.
Faulty RASC fan at heating
operation
Faulty RASC fan motor
Measure coil resistance and
insulating resistance (*)
Replace RASC fan motor if
faulty.
?
N O T E
(*): When the alarm code “47” is indicated, the RASC fan motor may be damaged. Ensure that fan motor is checked according to the
“10.4.3 Fault diagnosis of fan motor”
.