Check the easy things first: the thermostat is set to COOL and below room temperature, the filter is clean, and the breaker for the outdoor unit hasn’t tripped. A clogged filter is the most common cause; it starves the indoor coil of air until the coil freezes into a block of ice.

If you see ice on the refrigerant lines or indoor unit, turn the system off and set the fan to ON to thaw it before calling. Other common causes are an outdoor coil caked with dust, a failed capacitor that keeps the outdoor fan or compressor from starting, a refrigerant leak, or leaky ductwork dumping cold air into the attic. A system that’s too small for the house can also run all day on a 110-degree afternoon without catching up.

AC repair is offered by our St. George & Hurricane team, which answers around the clock with 24/7 emergency HVAC. AC repair isn’t offered in Flagstaff, Durango or Jackson.