Daikin FTXS09HVJU - Four-Way Valve Abnormality

Troubleshooting SiUS04-904
Service Diagnosis 115
4.11 Four-Way Valve Abnormality
4.11.1 09/12 Class
Remote
Controller
Display
EA
Method of
Malfunction
Detection
The indoor air 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.
Malfunction
Decision
Conditions
A following condition continues over 10 minutes after operating 5 minutes.
 Cooling / dry operation
(room temp. – indoor heat exchanger temp.) < –9°F (–0.5°C)
 Heating
(indoor unit heat exchanger temp. – room temp.) < –9°F (–0.5°C)
Supposed
Causes
 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
 Refrigerant shortage