You are low on coolant to the heater core.
There are several causes that an air conditioner is only blowing cold air for a short period of time then only blow hot air and then not going back to cold. This is especially common in the hotter weather including in the 90s and above. It could be from the air conditioner freezing over. You can fix this by simple trouble shooting and if that doesn't work call a repair man.
that usually means that you turned off the A/C on a higher degree. If it was cold in the morning and you had the A/C on 90 degrees, then turned it off, even when the A/C is off it will still blow out hot air. Vise Versa. If you had it at 65 degrees, turned it off, the air will still blow in cold.
Your A/C needs recharged.
Your compressor has possibly stopped working. If you are lucky, the serviceman will only have to replace the freon to get it going again.
Because something is wrong with it. When it is off it does`nt blow anything, that `s why you only notice it when it is on.
I would get it checked out by a profesional because that one is a hard one to deal with if it doesnt get done right
Because you set it that way
Vents are uaually operated by vacuum. Chances are, you have a vacuum leak at the directional valve or at the back of the air controller itself. All of these are in or under the dash. Good luck.
You have a vacuum source at the intake manifold that is possibly disconnected.
the AC is run by a belt that is connected to the engine. if you turn the engine off, the belt stops moving. No belt movement means no power for the AC. the fan will only blow air, not cold air.
check the free on in the compressor and if that's not it you will need a new compressor
why does ac blow warm air? why does ac blow warm air?