No cold air

[rober]

My AC blower is working but no cold air comming out. I checked the compressure and cooling fan and found that neither one of them is running when AC is turned on. Is the cooling fan suppose to be on every time AC is turned on. I'm not sure how to tackle this issue. Any help will be appreciated.

[meistermind]

What year and engine is your vehicle?? By "cooling fan", do you mean radiator cooling fan, or the blower fan in the dash?

First check the AC control circuit fuse inside the car (glove compartment I believe). Use the owners manual to list the correct one and rating. Then check the larger fuses/fusable linke in the engine compartment circuit box (passenger side on fender well perhaps). I believe there's one for the AC Compressor. If all apear intact, turn the AC on and measure DC voltage coming up the wire(s) connected to the AC Compressor. Disconnect from the Compressor first and measure at the wiring connector. GM should be a green only or green and black. If its green and black- then black is ground when measuring. If green only- then use the engine metal or battery negative as ground when measuring. If the Ac circuit is turned on and working it will be supply 12+ volts to this connector to try and activate the compressor clutch. If there is voltage present, but no AC Compressor Clutch engaging- then the AC Clutch Coil could be bad. Verify a good ground first.

If there is no volts at the Compressor wires, then it could be just because the system is too low on freon to turn on. This is common after not being used for the winter season. There is a pressure switch usually on the side of the Accumalator/Drier (the big metal can inline with the AC line from the Compressor to the firewall). The pressure switch detects a high and low condition and cycles off the Compressor if either exists. You can bypass/jump this switch to see if it then allows power to the AC Clutch- it will engage if so. Do not run the AC Compressor for very long with this switch bypassed, since the compressor will just continue to pump unregulated until it fails (The pressure switch makes the system safely and efficiently cycle normally). If the Compressor does come on, then the pressure switch could be bad, but.....you can just try to add freon first. Hook the pressure switch back up first, so the compressor can automatically start to come on when enough freon (minimum low pressure) is detected. The compressor will have very short cycles at first, but will increase as enough freon is entered. Most charge kits come with a hose and gauge. Monitor the gauge when the compressor is engaged, and charge with freon until gauge needle draws down into the green or "good charge" zone.

If your system is old enough (usually pre '94) to still use R12 freon, then I would convert it to R134 at this time. You can get a kit at about any auto store for $30-40. R12 is no longer available over the counter without a AC license so it is quite expensive. R134 is available at all auto stores.

[rober]

Thank you Meistermind,

Turns out that the system is low on refrigerant. I refilled it and it worked fine.