Restricted Airflow Across the Coil
When airflow through the indoor unit is too low — usually from a clogged filter — the coil surface cannot absorb enough heat from the room air. The refrigerant inside over-cools and the moisture in the air around the coil freezes. The fix is to restore airflow, not to add refrigerant.
- Airflow from the indoor unit is weak or significantly reduced.
- The filter has not been cleaned in a long time.
- Cooling was fine until recently, then weakened around the same time as the ice appeared.
We clean or replace the clogged filter, inspect the evaporator coil for dirt buildup, and retest airflow and coil temperature to confirm icing stops. If someone recommends a gas top-up without checking air flow first, push back. Restricted airflow and low refrigerant both cause ice on the pipe. They need different fixes. The cheaper check comes first.