Bad Air Compressor? AC bit the dust...

[bmwracerchick]

So for the past couple of months I have noticed the AC would kind of make a PHISHHHH sound every few seconds when I was at a complete stop or parked and the car's RPMs would drop slightly. I was thinking that I needed new refridgerent and my dad finally had the oppertunity to check for me if it was. He has worked on all our cars ACs before and he is in the AC business so he had the equipment to check how low the refridgerent was. Well It turned out it was fine but as he was trying to check the pressure my car was stuttering a lot and dropping RPMs like crazy every few seconds as I pushed on the gas in park. He thought I wasnt keeping it steady. He figures it might be my air compressor, and I have that suspicion as well. So now its shot, when I drive even normally with it on my RPMs would drop from 3 to almost a 1 then back up as I drive and or accelerate but then 5 seconds later it drops again. So I wont be driving with the AC, just the fan for a while. Problem now is we have a lot of rain coming our way from the first hurricane of the season, so I dont want to drive without the defrost option, it will get foggy very quickly with no AC.

So, my question is if anyone has had this problem before and how much it was to fix it, how much a air compressor might be, or even if they think that it is the air compressor and not something else. I would appreciate the advice, im hoping to get the car looked at on Tuesday or Thursday to get some quotes on it, but I cant live without AC lol

[bmwracerchick]

no one has a possible answer to my problem? lol or is it you have no idea what im talking about

[andyman7931]

I'll take a guess at this one. It sounds like your compresser is shot. Possibly it's hard to turn which causes a huge drag on your engine if I understand your problem correctly. If you take it to a shop, they'll probably want to replace the compresser and dryer, they should pull a vacuum to test for leaks and then refill. If you do it yourself you could possibly get away without replacing the dryer, adding coolant without pulling a vacuum will work, but may not be as efficient. I've hacked together some e30 systems this way (using r12 compressers on r134a) and it's worked fine for years afterwards, but don't know how it'd hold up to Floridia heat. If it were me, I'd get a used compresser and install myself (I may even have a spare compresser if the m50 ones fit the ti)

[bmwracerchick]

Thanks andyman, this thursday im getting it taken to get looked at. If it is the compressor and if the m50 works on our cars how much would you want for it?

[BonesOfSteel]

My car does the same thing. When I am sitting in traffic with the ac on, my rpm drop from 800 to 500. It also causes my car to jerk forward when it raises back up if I am not pressing on the brake very hard. I had that shhh sound awhile ago but I don't think it does it anymore.

[pdxmotorhead]

A low charge will cause this as well as overcharging.....

Dave