Why does my central air unit keep running after the indoor unit stops?

Answer by  dlstevenson (19)

I have to assume from your question that you are saying that your condensing unit outside continues to run, the most likely cause is a sticking or fused contactor. There are several causes for this condition, ants, water causing fusion or incorrect wiring at the thermostat. this should be an inexpensive repair.

Answer by  ishiee (84)

It will continue to run after the indoor unit stops to keep the system "at the ready" so when you need it its available.

Answer by  Ionoone (112)

Have it serviced by a proffessional, Most likely youll need to have the contactor replaced, Should be a fairly cheap repair with a reputable qualified air conditioner tech.

Answer by  Randy76 (95)

In most cases when this happens it is the contactor staying stuck. It is really the only reason the outside would stay running.

Answer by  Egon (67)

If your upstairs unit is clogged, the outside unit will keep compressing the gas, but no heat transfer will happen. Another explaination would be that you have iced up the interior coils, the compressor has reversed the flow of freon to heat up the interior coils to melt the ice.