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SiUS12-928_B
Troubleshooting for Indoor Unit
Service Diagnosis
148
5.2
Freeze-up Protection Control or Heating Peak-cut Control
Remote
Controller
Display
A5
Method of
Malfunction
Detection
Freeze-up protection control
During cooling operation, the freeze-up protection control (operation halt) is activated according
to the temperature detected by the indoor heat exchanger thermistor.
Heating peak-cut control
During heating operation, the temperature detected by the indoor heat exchanger thermistor is
used for the heating peak-cut control (operation halt, outdoor fan stop, etc.)
Malfunction
Decision
Conditions
Freeze-up protection control
During cooling operation, the indoor heat exchanger temperature is below (32°F (0°C).
Heating peak-cut control
During heating operation, the indoor heat exchanger temperature is above 149°F (65°C).
Supposed
Causes
Short-circuited air
Clogged air filter of the indoor unit
Dust accumulation on the indoor heat exchanger
Defective indoor heat exchanger thermistor
Defective indoor unit PCB