AC Blowing Warm Air

It means the fan motor is running. The compressor can be dead or weak while the fan spins, and a heat pump can run in the wrong mode. Feel the air coming off the top: on a working unit in summer it is noticeably hot. Cool air off the top of a running condenser is a sign the compressor is not moving heat.

With the system shut off at the thermostat, a gentle rinse from a garden hose on the outside of the fins is a reasonable homeowner task. Keep the pressure low, do not use a pressure washer, and do not remove the top or any panel. If the coil is badly matted, a technician cleans it with the right chemistry from the inside out during an AC maintenance visit.

Look at the thermostat. If it offers an EMERGENCY HEAT or AUX HEAT option, you have a heat pump. If the outdoor unit runs in winter to heat the house, same answer. Many Phoenix-area tract homes have heat pumps, and a stuck reversing valve is a plausible cause of warm air on them.

Slightly warmer supply air on a 115-degree afternoon is normal. Air that feels the same as the room is not. The system should still produce a clear temperature drop between return and supply, even on the worst day of the year. If it does not, something has failed.

We can, and on a slow leak in a newer system it is sometimes the sensible bridge to a scheduled repair. But refrigerant does not get used up. If it is low, it leaked. We will tell you where, what it costs to fix properly, and whether the system's age changes the answer.

We will talk you through the safe checks on this page, and the more detail you give the dispatcher, the better prepared the technician arrives. A firm diagnosis needs a meter and gauges on site. We do not guess at a repair from a description, and we would be wary of anyone who does.