Between the time of my original post and the present, I did some work/reading and I think I may be getting closer to solving the issue. 1- I may have to find out which relay(s) play(s) a role in the hvac function and test those. Which i will do if #2 doesn't pan out. 2- I was told that the alternator was bad, even though the battery was charging fine. So I swapped out the alternator yesterday and this may have solved the issue. The HVAC didn't come on immediately, but it did after I ran the car for a bit, so I'm thinking maybe it had to do with the constant voltage of the battery. Is it possible that an improperly charged battery could start the car yet not deliver enough power to the hvac compressor/fans/computer/relay? I will report back. [6/28 update: okay. new alternator did not solve the issue . (duh?) I will pursue #1.] Any feedback would be much appreciated. [old post follows:] "Greetings fellow bmw-o-philes. My '96 328i HVAC system shuts down very frequently, although when it works, it works okay. The heat works, A/C blows cold, and the cabin fans work. However, sometimes it just flicks off and the HVAC lights on the dash go dark and nothing HVAC-related works. I checked the fuses, and they're fine. I'm wondering if maybe it's a computer issue. The corner of the A/C heat exchanger on the passenger side is bent towards the rear of the car, but the A/C works fine, and I doubt that damage is relevant to my problem. Otherwise the car is in good shape. Any ideas about how to go about diagnosing or fixing this problem would be sincerely appreciated."
http://www.macadamizer.com/bmwfix.html http://forums.pelicanparts.com/showthread.php?t=356298&highlight=climate capacitor
Make sure the symptoms fit. The capacitor seems very possible. Yours does not sound like the final stage resistor problem which is the most common problem.
It worked! Thank you Jeron. I used the 47 uF Electrolytic capacitor from Radio Shack (47µF 35V 20% Radial-lead Electrolytic Capacitor$1.19 . Model: 272-1027. Catalog #: 272-1027). I don't have a lot of soldering experience so i basically melted some solder back, yanked the old capacitor out and installed the new one and -- my hvac is working now. Thank you again! I'll keep everybody posted if anything changes.
I sent my control unit off to bmwrepair.com in New York. Eddie Cobas is the guy's name. He repaired it for $49.95 plus the cost of shipping it back to me. It has worked like a charm ever since. I would highly recommend this service.
