Thread: My ac unit at home blows air through the vent even when the thermostat is

set to the "off" position? My ac unit at home blows air through the vent even when the thermostat is set to the "off" position. I will turn the unit off and it will shut down but as time goes on it will start to blow air through the vents as if the unit was on. It will continue to cycle on and off throughout the day. I have noticed that it only happens when it is warm outside. Any ideas on what could be wrong? It is a central unit with the furnace in the attic and the compressor outside.

there is a manual fan switch on the thermostat. check to see it it is on "auto" or "on". Put it on auto. If that doesn't work, you have bad thermostat.

If you have it set for off and it continues to work then the control is faulty right? Change the thermostat. The unit only does as told.

if you have a fresh air intake in the system, the damper might not be sealed correctly and you might be getting a draft. If that is not it, you might have a drft in the attic that is finding its way into the ductwork.