Frozen Coils: Needham's Most Misread Emergency
The call usually comes in as 'the AC is running but the house is not cooling.' In Needham, the cause is very often a frozen evaporator coil, and the two usual culprits are restricted airflow and low refrigerant charge. Retrofit systems in this town frequently have return ducts sized for a smaller original house, so a dirty filter that another home would tolerate pushes airflow below the threshold where the coil starts icing. Once ice forms, the system cannot cool at all and the compressor slugs liquid refrigerant — which is what turns an inexpensive service call into a compressor replacement. If you see ice, switch cooling off and the fan on before we arrive; that thaw time lets us actually diagnose rather than wait two hours in your driveway.


