A coil ices when its surface drops below 32 degrees F: low airflow from a dirty filter, a weak blower or closed registers; low refrigerant charge; a restriction; or running in cool weather. Ice blocks the coil, which cuts airflow further, so it snowballs. The fix starts with shutting off cooling and running the fan to thaw, then finding the cause; chipping ice off fins destroys the coil.
Whole coil's iced up and the line's frozen back to the condenser, shut the cooling off, run the fan, and pull that filter.
Also heard as
- iced
- frozen coil
- freezing up
Related terms
Evaporator
The coil or heat exchanger where low-pressure liquid refrigerant boils off, absorbing heat from air or water.
Starved
Describes an evaporator not getting enough refrigerant, so part of the coil runs warm and superheat is high.
Static pressure
The pressure air exerts outward on duct walls, the resistance a fan works against, measured in inches of water column.
Defrost
A cycle that melts frost off a heat pump's outdoor coil or a refrigerated evaporator so it can keep moving heat.