Carrier Evaporator Coil Issues — Leaks, Freeze-Ups, and Corrosion

Your Carrier evaporator coil sits in the air handler, usually in the attic or garage. You can't see it without taking the cabinet apart — which means the problems creep up on you.

Formicary corrosion (the silent killer)

Microscopic tunnels eat through copper coil tubing from the inside out. Cause: organic acids from indoor VOCs — cleaning products, new carpet, paint, even some air fresheners. Florida homes are sealed shut for AC use, which traps the VOCs in the air the system processes 24/7. Carrier moved most residential coils to aluminum micro-channel after 2015, which is largely immune to formicary. Older copper-tube coils are vulnerable.

Freeze-ups

When airflow drops or refrigerant charge is low, the coil temperature drops below 32°F and ice forms on the fins. Once a coil is iced over, no air can pass through it — the system runs but doesn't cool. Common causes: dirty filter, dirty coil, blower motor problem, closed return vents, low refrigerant from a leak.

Coil cleaning

Even with no leak, evaporator coils foul over time with dust, pet dander, and biofilm. Performance drops 15–25%. We pull the coil during maintenance to deep clean — see our case study on the Port St. Lucie evaporator coil pull and clean.

When the right answer is replacement

A leaking evaporator coil on a system 10+ years old usually isn't worth repairing. Carrier coil replacement runs $1,500–$3,500 in parts and labor; a full system replacement starts around $7,500 and resets your 10-year warranty. We'll lay out both options in writing so you can decide.