AC problems ????? - United Bimmer Community

**barracuda6073** · 07-13-2009, 04:29 PM

Hey all Im having Ac problems the clutch is not engaging on the compressor I was doing some research in my bentleys manual and it says theres an inline diode ? Bmw said its prolly a bad relay ? anybody have any clues ?
And does the Aux fan only come on when the ac is on ?
Any ideas would help
thanks

If youve never driven the Autobahn A8 from Munich to Salzburg you dont know what your missing !!

Big Evil · 07-15-2009, 02:54 PM

Could be the relay, could be either of 2 (depending on you model) pressure switches located on the receiver/dryer. Could be low charge, aux fan works off of the ac normally. Need a little more info. When did the ac stop working? Did it make any unusual noises? What's the state of charge in the system? Is it still R12 or has it been converted to 134a? Did the seals get replaced w/the right stuff? Has there ever been any of that nasty stop leak garbage in the system? Could be a bunch of stuff or it could be really simple.

**barracuda6073** · 07-15-2009, 07:37 PM

Hey thanks for the info I was just out checking it over yea the coolant is very low I depreesed one of the shrader valves on the lines and a slight hiss came out So Im guessing that means theres not any bad leaks or itd be dry??
No clue if its 112 or 134 ive only owned the car 3 months and it hasnt worked since I owned it Should I take it to an ac mech or just get one of those 134 conversion kits from discount auto parts????
thanks patrick

Big Evil · 07-15-2009, 08:17 PM

Conversion to R134 is not hard but it has to be done right. If the charge is gone, you'll need to disconnect all the lines and fittings one at a time and replace all the black rubber o-rings with the brown R134 o-rings. There are fittings under the hood, on the receiver dryer (which you'll want to replace) and at the compressor. Then there are fittings under the dash at the TXV valve (take out the glove box and trim to access it). You'll then need to acquire a vacuum pump and once you put the R134 fittings on the system, pull it down into a vacuum for about an hour at least (this is done to remove ALL moisture and air from the system, also leak check). Then using the manifold gauge you'll already have attached, push a vapor charge in through the low side port (stay the hell away from the high side it'll hurt/kill you if it goes wrong). Fire the car up and continue charging the low side until the compressor kicks on and stays running. You'll need to monitor the register temp as well as the low side pressure, USUALLY 25-35 psi on the low side is about right, over 50 or so and that's bad. R134 will only need to fill to about 80-85% the capacity of R12. When its done you need to fill out the conversion sticker and affix it to the shock tower. You could take it to a tech they'd have to do the same stuff but w/the R12. The only thing is do you KNOW where the leak is? Did a seal blow or did your compressor give up the ghost? If you have to buy a compressor, convert it. One other thing NEVER use a product that has "stop leak" or "seal enhancer" or "synthetic cold booster" it's all the same crap and will lead to another failure and EXPENSIVE need for parts replacement (it gums up in the presence of air and is actually a system contaminant, most shops will refuse to work on your vehicle if it has any in it, and if they don't they're stupid, it destroys equipment). Basic el cheapo nothing added R134a IS the best stuff to use PERIOD.