Specifications

Troubleshooting SiUS12-928_A
121 Service Diagnosis
5.15 Four-Way Valve Abnormality (18 Class)
Remote
Controller
Display
EA
Outdoor Unit LED
Display
A 5 1 4 2 1 3 1 4 1
Method of
Malfunction
Detection
The liquid pipe thermistor, the outdoor temperature thermistor and the outdoor heat exchanger
thermistor are checked to see if they function within their normal ranges in the operating mode.
Malfunction
Decision
Conditions
Either of the following conditions occurs 6 minutes after the compressor has started.
 Cooling operation
Lowest temperature among the running indoor heat exchangers > 5°C (41°F)
 Heating operation
Highest temperature among the running indoor heat exchangers < 0°C (32°F)
Supposed
Causes
 Poor connector contact
 Defective thermistor
 Defective outdoor unit PCB
 Defective four-way valve coil or harness
 Defective four-way valve
 Foreign substance mixed in refrigerant