This may stump you! AC Problem

[cal45fan]

A friend who has a 98 528i has this problem. She turns the car on and the HVAC control turns on by itself (like it was left wit the AC on, after shutting off the engine). Eventually, the car will cut off.

So what she does is she gets in the car, puts the key in Position II, turns off the HVAC, then, proceeds to start the car. Car runs fine. If she turns the AC on, the car shuts off...:help

Summary: For as long as the HVAC control is off, car runs fine. As soon as the HVAC is on, the car dies...

[NNY528I]

check the IAC valve for proper operation, sounds like it has failed.

[cal45fan]

Do you think that it is clogged so bad that it kills the engine? Any other symptoms that may be a precursor to the problem before it reared its ugly head, like poor accelertion?

So, why would the HVAC control be on as soon as she turns the ignition on eventhough she did not leave the A/C Control on before shutting off the car?

[crdiscoverer]

I think Jason posted a similar issue a few days (hours?) ago. It turned out to be the fuel pump, as strange as it sounds. Talk to him to see if it looks like the same thing.

[cal45fan]

I think Jason posted a similar issue a few days (hours?) ago. It turned out to be the fuel pump, as strange as it sounds. Talk to him to see if it looks like the same thing.

Jason? Jason5Driver?

[Twinair]

check the IAC valve for proper operation, sounds like it has failed.
+1

[crdiscoverer]

Jason? Jason5Driver?

Yep, let me find the thread.

Here it is:
http://forums.bimmerforums.com/forum/showthread.php?t=1471385

[m5hoot]

When the AC is on, the idle is supposed to raise by 100RPM so I agree that it could very well be the IAC valve. However, since you said it does not die immediately, but *eventually*, I wonder if the compressor is seizing-up after it warms up. What happens if she is driving at highway speed and turns on the AC? Does it work just fine and stay cool for as long as she does not slow down?

[e39dream]

Idle control valve does most of it's magic on a cold engine, allowing additional air in to keep idle smooth until the engine is warmed. I've pulled an ICV out of my 528i that was totally seized inside (as in not at all working), yet the RPM would still raise by 100 RPM when you turn the AC on. This leads me to believe the ICV is not the issue for your friend.

Bill might be onto something, maybe the compressor is locking up here and there causing the belt to drag.

[cal45fan]

Yep, as it turned out, it is the compressor locking up. She pickep up a compressor (rebuilt), accumulator (new), expansion valve (new) from AAPAK.com for $300 with 1 year warranty. I thought I'd share that. Thanks for the help, folks!!!