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Discussion Starter #1
I recently bought a '99 540i 6 speed. The A/C wasn't working, and the seller said their service provider told them the A/C won't go on until the ambient temperature is 70 degrees or higher. I had a PPI done at my service provider and they told me the A/C was in need of a recharge, and that they had never heard of the 70 degree or higher requirement for the A/C to work. Now that I have the car in for service, turns out the climate control is bad :(

Is it possible the A/C really isn't working because it's not 70 degrees out? Seems like a crazy feature, but I thought I'd ask on here before getting the climate control replaced.

Thanks --

Keith
 

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Freude am Fahren
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FSU Final Stage Unit is another way of putting it if you're searching.

A/C would have to kick in at <70 because the climate control in my car goes down to 61***8230;
 

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Discussion Starter #5
I searched on FSR/FSU and that doesn't seem to be it. The fan blows, heat works fine, the A/C just doesn't blow cold. Any ideas?
 

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You may also want to check your owners manual...your Climate Control system is explained and the temps at which certain features of the system are implemented or can be initiated is explained.

If you don't have an owners manual..you can download a manual in PDF format (makes it much easier to "search") from www.e38.org/e39 . You will find many e39 manuals at the bottom of the LEFT column. If your model year is NOT listed...download the one that is CLOSEST to your model year. There aren't that many differences during the production run that can't be extrapolated to your model year. For instance, if you had a 1997 e39, then sat in a 2003 e39...you'd understand how to operate everything...except maybe the NAV system. But if you did have an e39 with the old NAV system and got into one with the newer WIDE screen NAV...again, the controls will basically be the same.

As you can see in the info below...the AC system will operate down to 42 degrees (F)...which allows the system to DEHUMIDFY the air within the cabin which helps with eliminating condensation building up on the windows. BTW, another example of the continuity of operations BMW uses...the info below is from he E38 owners manual...and you can see that the operations are exactly the same...as well as the icons on the buttons and the function of the IHKA control panel:

 

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I searched on FSR/FSU and that doesn't seem to be it. The fan blows, heat works fine, the A/C just doesn't blow cold. Any ideas?
First, what does your outside temperature sensor read? If it is correct disregard. If it is missing or reading erantly, this will affect your AC operation.

Second, does the compressor cycle on and off below 70 (you would not feel this cycling but would "hear" this at idle with the hood up. It would sound like the engine momentarly having a load on it (drop in RPM) and then having the load removed (RPMs jump up). If so, you are low on refrigerant charge. If the compressor does not cycle you have an electrical short somewhere in the line.
 

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Discussion Starter #8
Thanks for the info. everyone. I'll check A/C operation with the hood up and see if I can detect the compressor going on or not. If it's not, sounds like the diagnosis is a fuse, or bad climate control?
 

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Discussion Starter #11
Update: I can hear the compressor kicking on when I push the A/C button, but no cold air blows, even though it's just been recharged. Climate control?
 

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If everything else works, I doubt its the climate control. If you want to talk to the expert, call Michael at BMWHVAC.com My guess is he knows whats going on with your car.

He doesn't fix E39 units but knows just about everything that has to do with BMW's hvac stuff.

His # is (516)729-2003 - he's a super cool guy and hooked me up with a reman climate control module for my 5er.
 
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