HVAC Problem Diagnosis · Phoenix Metro
Frozen AC Coil
A frozen evaporator coil usually means the coil temperature dropped below freezing because of restricted airflow or a refrigerant problem. Running the system while it is iced over can make diagnosis harder and may stress the compressor.
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Possible causes
- Dirty air filter
- Restricted airflow or blower problem
- Low refrigerant from a leak
- Dirty evaporator coil
- Control or metering issue
Safe checks before calling
- Turn cooling OFF if the coil or refrigerant line is iced
- Set the fan to ON to help thaw the coil
- Replace a clogged filter
- Do not chip ice off the coil or add refrigerant without finding the cause
The symptom is not always the failed part
Many HVAC failures create the same symptoms. A failed capacitor can look like a compressor problem. Low refrigerant can look like an airflow problem. A float switch can make a healthy system appear completely dead. Sapper HVAC starts with diagnosis so the repair is based on what actually failed.