What Is an Evaporator Coil?

The evaporator coil is the indoor coil where cold refrigerant absorbs heat from air passing over it. As the air cools below its dew point, moisture condenses on the coil and drains away — which is how an air conditioner dehumidifies as a by-product of cooling.

Also called: indoor coil · A-coil · evaporator

Why it matters to you

On the Crystal Coast the coil's dehumidifying role is as important as its cooling role. A coil that never runs long enough, or that is starved of airflow by a dirty filter, cools air without removing much moisture, which is why a house can feel clammy at a thermostat setting that should be comfortable.

What to do about it

Keep the filter clean and the condensate drain clear — a blocked drain is a common cause of water damage and of safety switches shutting the system down. Coil cleaning itself is a service task, because the coil is awkward to reach and easy to damage.