I just thought I'd run this by and see if anyone might have any guesses as to what would cause an A/C unit to blow cold air for several hours and then warm air (80º-86º depending on the time of year)? Scenario: Thermostat set to 75º. Inside temperature is maintained at that temperature for 8 to 12 hours. After that time period, the blower fan continues to constantly run but inside room temperature reaches up to 86º. I turn the thermostat off, go to work (10 hours), come back home, turn the A/C unit on and the temperature goes back down to 75º. This same scenario repeats on a daily basis.

 

What kind of A/C is it? Central? In-window? Mini-split?

 

Welcome to the forums.

If the inside blower is always working ok..... then you need to focus your attention outside.

You could have a defective fan motor.
A defective capacitor.
Low on refrigerant...... possible leak.
Defective contactor.

All just guesses as we can't see what you have there.

 

Go clean the coils good. that is a good place to start then get back to us--use a hose- and if super super dirty- use a broom or gentle brush--in direction of fins--not against the grain so to speak- you dont want to bend them. Once you get all the hair, yard clippings and junk off- use a hose and wash them out from the inside- spraying in thru the fan (with it off of course)---and do as much as you can and then hose off from outside.

That is a likely situation---(until we have more information)----and- it will only help if this isn't the problem.

 

Thanks for all of your replies.

RocketJSquirrel it is Central A/C (Heat Pump). The unit is on the rooftop of a two-story apartment building.

Thanks for the welcome. Pjmax and mtsaz, I wasn't sure if the thermostat settings on the back side of the thermostat panel might be the culprit since there are some small installer switches back there (HP/Conv, 1st and 2nd stage temp. differential settings, etc.) but I will try and sneak up there and check the cleanliness of the coils and troubleshoot the components with a meter and check for leaks. At least now I know where to start, and I'll get back to you all (if the property maintenance guy doesn't catch me up there).