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Discussion Starter · #1 ·
Alright I've read every thread on this topic google can find to the point every single link is purple because I've already clicked on it.

My problem is simply that my a/c compressor will not engage.

Here's what I've done to no avail:
Checked fuses in glove compartment and above battery.
Changed FSU (fixed fan speed).
Applied direct power to compressor and it engages fine and blows ice cold. Also checked pressure with compressor engaged and it is normal.

Everything works on the control panel and all buttons light up but it the compressor simply won't engage.

AUX fan takes a few minutes to engage but once it does it functions normally. Is that normal?

I checked the voltage of the plug that connects to the compressor and found it reads about 8 volts. Does not change when snowflake button is pressed or not (green light on or off).

Please help. I'm at a dead end and I can't take the 100+ degree weather with serious humidity in my black car...
 

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I would expect 0V there, since this output has low/high functionality only. I might measure this later if I got a chance.

However the behavior of the aux fan (should go on immediately) shows that the A/C control module doesn't even try to turn on the AC.
 

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How does the speed of the blower motor change in auto mode when you go through all the temperature settings from min to max?
 

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Discussion Starter · #8 ·
Completely normal... Just checked. I'll turn it on auto with it set at 60 and the fan will blower motor blows at max but as I turn the temp up the blower motor decreases.
 

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Do you have access to INPA diagnostics? If you do, you can turn on the compressor using the program which would verify a open or closed cicuit. My E39 had a simlar situation were the compressor had been thrown into "transport lock mode" due to IHKA panel errors. (believe it or not ,this was caused by installation of a aftermartket radio) INPA can unlock this and will allow compressor and aux fan to run normally.
 

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I have measured the voltage at the compressor and it is 8.9V with the AC off.
 

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Discussion Starter · #11 ·
No, I don't have access to INPA diagnostics... That is something I would really love to explore because I didn't have any issues with the AC until I installed my Dynavin unit... Is there anyway to just reset the system completely to get rid of the error? I have installed my stock radio back in until I get this thing figured out. Could an FSU cause the AC clutch not to engage only? Just checked my FSU and it turns out to be a Behr one that was made in China. Before I spend $100 dollars at the dealer I want to make sure it's not money wasted. I've reinstalled my old FSU and my fan speed problems came back obviously but still no AC clutch engaging.

Also thank you acoste for checking on that. At least I know that's normal.
 

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No, I don't have access to INPA diagnostics... That is something I would really love to explore because I didn't have any issues with the AC until I installed my Dynavin unit... Is there anyway to just reset the system completely to get rid of the error? I have installed my stock radio back in until I get this thing figured out. Could an FSU cause the AC clutch not to engage only? Just checked my FSU and it turns out to be a Behr one that was made in China. Before I spend $100 dollars at the dealer I want to make sure it's not money wasted. I've reinstalled my old FSU and my fan speed problems came back obviously but still no AC clutch engaging.

Also thank you acoste for checking on that. At least I know that's normal.
PLEASE READ THE LINKED PAGE BELOW!!!! You will find most of your answers!

http://forums.bimmerforums.com/forum/showthread.php?t=1717934&page=22

The symptoms you are having are described in this thread. If you do have a Dynavin (as I do) please remove the ibus box temporarily and contact your seller. IHKA panel will have to be reset and unlock the compressor with INPA. (especially posts# 533-537)
 

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Discussion Starter · #13 ·
That has been my problem EXACTLY every since I installed the Dynavin!!! Is buying INPA the only way I can reset my HVAC control module? I would really like to find a way around buying that just to reset a module.
 

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Unfortunately, that is the only way I know of to unlock the compressor. May want to seek help on the forums if there is another way of doing this. Maybe check with some other members in the forum that may be near your area that have access to INPA and ask for some assistance.
 

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Okay, I'm on a college studen budget, so any helpful information will be greatly appreciated.
2001 e39 503i
Compressor is working
Climate control unit works
Blower is working
Fuses are good
There is no relay to this system
When I hook up ac gauge to system, it trades in the red. The instructions said to have the unit service and not to put any freon into the system.
So it seems there is a blockage somewhere in the system for the gauge to read in the red
What could be blocking the freon and preventing the compressor clutch from engaging.
 
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