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HVAC prbs

4K views 8 replies 3 participants last post by  tranquility 
#1 ·
My HVAC controls (the green lights in all 4 circles don't light up, so there is no function at all) would not work about 10% of the time I start up the car. So the dealer diagnosed the prb and supposedly it was a faulty control unit, which was subsequently replaced. However, the prb still occurs: not sure if you guys have any ideas what it could be? It is very weird because it still works but sometimes it doesn't.
 
#2 ·
Hi! when all of the lights are off have you tried to switch the blower on for example? It could be a faulty relay or a loose fuse as it appears to be a power issue!!!! even though the control unit has been replaced.
 
#3 ·
I have tried pressing all the buttons but none of them work when my HVAC is acting up; when it works, it is fine, all functions go. I'm not technically-inclined, but I agree w/ your assessment...it must be sometime loose or a software glitch because my HVAC works most of the time.
 
#5 ·
given your car should still be under warranty, you should just take it back to BMW!! I did have a look on a Wiring diagram but it is only for the E85 Z4, 2007 just to see if anything was obvious, sadly I could not see anything.......
 
#8 ·
Didn't have this problem during ED. After dealer replaced iDrive control module and reprogrammed, I noticed this issue. Dealer did 'master reset'. But I am noticing this issue frequently. I am taking in the car today for the infamous 'Engine Malfunction, Reduced Power' issue. I will have them recheck the AC issue.
 
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