Evaporator Coil Repair & Replacement

The evaporator coil sits inside the air handler and does the actual work of cooling: warm household air passes over it, heat moves into the refrigerant, and the moisture that condenses out runs off into the drain pan. In Florida that coil is wet for most of the year, which is exactly the condition in which aluminium and copper corrode.

Formicary corrosion — the pinhole leaks caused by everyday household chemicals reacting with copper in a permanently damp environment — is the most common way a coil fails here, and it is genuinely difficult to see. The system does not fail loudly. It just cools slightly less well each month until someone measures the charge and finds it low with no obvious leak anywhere else.

Coil replacement is a job where the details decide whether it lasts. A replacement coil must be matched to the outdoor unit rather than merely fitting the cabinet, the line set needs to be clean, and the filter drier must be replaced. We also want to know why the original coil failed — because if the answer is airflow or drainage, a new coil in the same conditions has the same future.