Daikin AT12BV1LS Pocket Manual page 63

Troubleshooting
5.2.18 Four Way Valve Abnormality
Remote
Controller
Display
Method of
Malfunction
Detection
Malfunction
Decision
Conditions
Supposed
Causes
62
EA
The room temperature thermistor, the indoor unit heat
exchanger thermistor, the outdoor temperature
thermistor and the outdoor unit heat exchanger
thermistor are checked to see if they function within their
normal ranges in the operating mode.
A following condition continues over 1 minute after
operating 10 minutes.
Cooling / dry operation
(room temp. – indoor heat exchanger temp.) < –10°C
Heating
(indoor unit heat exchanger temp. – room temp.) < –10°C
Connector in poor contact
Thermistor defective
Outdoor unit PCB defective
Four way valve coil or harness defective
Four way valve defective
Foreign substance mixed in refrigerant
Insufficient gas
Si10-417
Service Diagnosis