AC took a dump

It's been really hot here in the Sunny Carolinas. All summer, I've had to crank out the AC. It worked as well it should for 20 year old car. Not great but good enough and a champ on the highway.

Today it went out. The fan kept blowing but the air turned hot really fast. I thought I had exhausted the freon, (I have the converted kind) so I went and bought a couple of bottles. The last couple of summers, I've always had to recharge it, but this summer it seemed to be going strong so I did not.

I went to put the little hose on and for some reason it won't snap on like its supposed to and the air was going out. When I did press hard on the hose, the gauge would jump up (like it was filled) and freon would come out.

Any ideas? I don't think its the fan because it blows air. I read on a thread that it might be the auxillary fan sensor?

Thanks for all the help so far in this forum. Idk wth I would do without you guys!

The valve that controls the heat could be stuck open. It is just aft of the drivers shock tower. Try blocking flow by clamping off the supply or return hoses.

Does the compressor run when you have the A/C switch on? If not it could be low freon pressure, a bad compressor clutch or faulty fuse/relay. If it does run, is the output hose fitting getting cold? If it does then you should be good to go and I'd do as bimmer-dot-info suggests and check the heater valve. If the fitting doesn't get cold then its probably a freon problem.

So I took it to a mechanic and he was able to get the compressor to come on by directly powering it. Once he pulled the power off of it, it would shut off. It has plenty of freon, but he said the switch was reading the pressure as too low (it was too low according to the mechanic) and not firing up the compressor. Any ideas?

If the pressure is too low then the system needs a re-charge. Either that or you have a faulty pressure switch. You could try by-passing the switch (jumper out the contacts) and see if the A/C system works normally i.e. cold. If it does then it is probably a bad switch. If it only works so-so or not at all then a re-charge is needed. Do not run the compressor for long if the pressure really is low as you might cause damage. The refridgerant also carries oil to the compressor to keep it lubricated and if pressure is low then it may not be getting enough oil.

When he jumped it, it was blasting cold air. He put three of the small cans in, but when he would take the power off, the compressor would shut off and the pressure would drop in the system. I guess if the compressor is off the system will read low pressure then?

Looks like it may be the switch?

If the compressor isn't 'compressing' then yes the pressure will drop. If everything is normal with the pressure switch jumpered then it is most likely a bad pressure switch.

Thanks!