Poltergeist in the A/C [Archive] - Bimmerfest - BMW Forums

: Poltergeist in the A/C

05-22-2010, 09:35 PM
I have a possessed a/c control system:
2008 535xi 60K miles. No problems except for the 3 fuel pumps put in under warranty.
3 times in the last month, the a/c has decided to quit while I was driving. Each time was after 1-2hrs on the road. Air stops coming out the vents, the rear vent in the center. A lot of noise like it was on defrost occurs but no air is coming out the windshield vents. Changing settings, turning it off/on, max off/on, defrost off/on does not change anything. Stopping the car and turning it off does nothing over 5-10min, but if I leave it off overnight, wallah! it works perfectly. Does not happen on short trips and I've been unable to get to a dealer to demonstrate the issue on the road.
Quit is probably the wrong term: no air flow where it should go. What little flow comes out the vents is cold.
Sounds like some type of flap/damper is obstructing flow??
Totally random events, goes for weeks without a problem....then....
Any ideas?

05-22-2010, 09:46 PM
set the car on fire.

05-23-2010, 06:27 AM
May be evaporator freeze-up? That could be caused by insufficient Freon. I've had the exact same thing happen on my home HVAC - when I looked in the blower unit it was all coated in ice and the ice cut off the airflow. The HVAC guys pumped in some Freon and that was that. I believe the same thing can happen in an automotive HVAC as well. Fits the symptoms - ice takes a while (overnight) to melt, short trips don't give enough time to freeze up, and when it freezes up and cuts the airflow, the automatic fan starts stepping up to compensate until it's roaring.

Oldman M Coupe
05-23-2010, 06:33 AM
Service Bulletin # 64 04 05, Programing issue.

05-23-2010, 11:37 AM
thanks for both suggestions
will give me a head start with the mechanics