check the free on in the compressor and if that's not it you will need a new compressor
my vent doors are not working in my 92 camaro. the heat will blow hot or cold but only on def
check thermostat, might be stuck closed.
Your A/C needs recharged.
You are low on coolant to the heater core.
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.
You have a vacuum source at the intake manifold that is possibly disconnected.
There is 2 possible problems -# 1 your a/c system is over charged . # 2 The temperature control valve is not working properly
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.
either you have a vacume leak under hood or the diaphragm is blown on vent selector
Compressor not running, blown fuse, low of freon.
Bad blower resistor? Bad low speed relay? Bad switch?