F2
Carrier Split AC
Severity: ModerateWhat Does This Error Mean?
F2 on a Carrier AC means the indoor coil (evaporator pipe) temperature thermistor has a fault. This sensor monitors the indoor heat exchanger temperature to prevent the coil from freezing and to regulate the refrigerant cycle. F2 triggers a safety shutdown to avoid ice formation on the coil.
Affected Models
- Carrier Ester Plus
- Carrier Superia Plus
- Carrier Durafresh Neo
- Carrier Inverter Split AC (all models)
- Carrier Ductable AC (inverter series)
Common Causes
- Indoor coil thermistor failed — open or short circuit in the sensor
- Thermistor clip dislodged from the evaporator coil pipe
- Thermistor wiring corroded or broken inside the indoor unit
- Dirty air filter severely restricting airflow — coil over-cools and the sensor reads abnormally low
- Indoor PCB fault causing incorrect thermistor signal
How to Fix It
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Clean the air filter — remove it, wash it under a tap, allow it to dry, and reinstall.
A blocked filter restricts airflow over the evaporator coil, causing it to over-cool. This can push the coil thermistor to its fault threshold even if the sensor is physically healthy.
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Switch off the AC at the remote and circuit breaker for 10 minutes.
If the coil was approaching freeze, this allows it to defrost before restart.
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Restart and observe — if F2 clears with a clean filter, the filter was the cause.
If F2 returns despite a clean filter, the thermistor itself has failed and needs replacement.
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Call Carrier service (1800-103-9999) if F2 persists after filter cleaning.
The technician will confirm whether the thermistor or the indoor PCB is the faulty component.
When to Call a Professional
F2 requires a Carrier authorised technician. Carrier India customer care: 1800-103-9999. A technician will test coil thermistor resistance and replace it if readings are outside specification.
Frequently Asked Questions
How often should I clean my Carrier AC filter to avoid F2?
Carrier recommends cleaning the filter every 2 weeks in normal use. In dusty environments, near-construction areas, or homes with pets, clean it weekly. A clean filter is the single most important maintenance step for preventing sensor-related errors.