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Discussion Starter #1
When I turn the climate control on Auto the front defrost vents act really strange. When I come to a stop they start blowing hot air at full speed and then when I pull off they stop blowing. I leave the temp set at 72 all the time, winter and summer, and this has only started happening recently. I do NOT have the front defrost button turned on. Also, there is the rare occasion where it will do this going down the interstate as well...blow hard through the defrost for few seconds and return to normal. When any of this happens, stopped or while driving, all the other vents seem to be operating as usual, it's just the front defrost vents that are acting up, and if I turn Auto off none of it happens at all. I'm under the impression that the climate control is fairly complex in these cars so I thought I'd see if anyone on here has any insight regarding these little gremlins that seem to floating around in my car.

Thanks
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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A technical description of the BMW IHKA HVAC is linked from the E70 forum Knowledge Base to a G00gle Drive file of perhaps two dozen such descriptions of various systems. I do not believe that BMW redesigns a major system for each platform. YMMV

If you have a component problem then it is most likely the condensation detector sensor. Mine is in the mirror mounted assembly and IIRC it looks at light reflecting from the moisture on the window.

You may not have sensor or system problem. The IHKA should always be in AUTO with a comfortable program toggled among SOFT, MEDIUM or INTENSIVE. The AC compressor should always be enabled with the snowflake icon button lighted. The AC evaporator enabled is ALWAYS fully loaded to dehumidify the incoming air and cabin. Select comfortable cabin temperatures and air distribution.

The IHKA is not intended to be frequently twiddled with, I have one infrequent occasion to override to Demist; after our half-hour ferry ride accumulating exhaled moisture while the BMW is off (I don***8217;t idle cars for long and don***8217;t believe that it is good for my diesel)>
 

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Discussion Starter #3
If I'm understanding this correctly, this is pointing to the sensor that is mounted in the rear view mirror along with the rain sensor for the windshield wipers.....which would actually make a lot of sense because I had the windshield replaced right before all this started happening. In my tiny little head I kinda had a feeling that the windshield replacement had something to do with it but I wasn't sure how to correlate it because of my lack of info regarding how the climate control works. I had Safelite replace the windshield and I'm pretty sure they didn't replace that sensor so I'm guessing something isn't right with the way they remounted it to the new windshield.
 

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I had an issue with the humidity sensor after a Safelite replacement. The sensor adheres to the windshield and Safelite simply tried to reattach the sensor with the old adhesive. I got various error codes for the sensor when checked with a code reader (no CEL though). I bought a new sensor and replaced it. Problem solved. CONDENSATION SENSOR 64116928326
 

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Discussion Starter #5
Yesterday I took the condensation sensor out and there was a big glob of the old adhesive stuck right in the middle of the little copper part of the sensor.....big thanks to Safelite for that. Anyways, I cleaned that off and used some double sided tape and everything seems to be golden. I checked for any codes with ISTA and didn't have any before it after I worked on it so I don't see any reason to replace it at this point and I drove 65 miles this morning with no occurrences.

Thanks for the suggestions! I thought it was really convenient that it started acting up right after my windshield replacement but thought I might be half crazy to think that my windshield had anything to do with it....but at the same time kept telling myself it's a BMW so there's no telling what they have for sensors or where they are!
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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