F4
Haier Split AC
Severity: ModerateWhat Does This Error Mean?
F4 on a Haier AC means the outdoor coil (condenser pipe) temperature thermistor has a fault. This sensor monitors the outdoor heat exchanger temperature to protect the compressor and regulate the refrigerant cycle. A failed or disconnected thermistor triggers F4 and the system stops.
Affected Models
- Haier Inverter Split AC (all capacities)
- Haier Turbo Cool
- Haier Pro Inverter
- Haier HREA series
- Haier HSUA series
Common Causes
- Outdoor coil thermistor failed internally
- Thermistor clip dislodged from the condenser coil pipe
- Wiring to the outdoor coil thermistor broken or corroded
- Connector at the outdoor PCB loose or moisture-damaged
- Outdoor PCB fault misreading the coil sensor signal
How to Fix It
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Power off the AC at the remote and circuit breaker. Wait 5 minutes and restart.
If F4 clears and the AC runs normally, monitor for recurrence. Persistent F4 confirms a genuine sensor fault.
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Ensure the outdoor unit has full ventilation clearance.
At least 30–50 cm of clear space on all sides. A blocked outdoor unit overheats the coil and can push a marginal thermistor into fault range.
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Call Haier service (1800-200-9999) if F4 persists.
The technician will test coil thermistor resistance and replace the sensor if it is outside specification.
When to Call a Professional
F4 requires a Haier authorised technician — do not open the outdoor unit. Haier India: 1800-200-9999.
Frequently Asked Questions
Is Haier F4 the same fault as F3?
They are related but not the same. F3 is the outdoor coil temperature sensor fault on most Haier models. F4 is a different sensor in the outdoor unit — either the discharge pipe thermistor or a second coil thermistor depending on the model. Both require a technician with the service manual for your specific model to confirm which sensor is at fault.