1994 e36 325i manual A/C control unit fixed!

[crash991]

Problem: A/C control unit buttons would not work. Car constantly blew hot air. Vent Knobs worked. Blower Knobs worked. A/C, Recirc and/or Defrost light stayed on even when A/C unit set to off.

I searched high and low for a fix, replaced the unit itself and still had the same issues. Checked all the fuses. the only time the unit worked was when i disconnect the negative battery terminal for 5 seconds. Even then it would only work for a day if that.

The Fix: Ebay. A/C control module part #64 11 8 391 512
This part came off of a 1992 325is. Cost: 19.95 free shipping.
As soon as I recieved I installed on my 1994 325i. Bingo! Now my A/C unit works.

Just in case anyone else is having this same issue. I was told i would have to take the module to BMW and have it coded. I figured since I bought it used it was coded...so I didnt bother. I have not had any issues yet.

Hope this helps someone with the same issues.

BTW....The module is located directly behind the center console below the on board computer. Remove the OBC by reaching underneath it and using one finger push up and pull from the middle. Then remove the console below it (just pops out). You will probably need to disconnect the Cig lighter and left heated seat control. The a/c control module has white, blue and black connecters. The Blue and White connectors have a "slide" on top that is used to remove them. The a/c module is not screwed in. It pulls right out but not too easily. Hope this saves someone some headaches!

[jenifer.kaif]

Thanks for the information.I would definitely try if same problem occurs.

[FIX]

Thanks for posting this! I think you and I might be the only people this has happened to. Everything I read on the net is about the fancy electronic CCM, not the analog one you and I have.

Symptoms are exactly the same for me, except that A/C, recirc, and defrost lights will never light up, or work.

I've not tried the battery disconnect yet, but will do so. I have the unit out of my car now, so I may bench test this to see if it's a simple capacitor failure that I can fix with a $.99 part from Radio Shack. I've torn my car apart looking for everything from a bad heater core to an electrical short. This unit has been looking me in the face this whole time. On the plus side, heater core appears to be fine and I didn't find any electrical shorts either... yay!

I'll post back and let you know how it goes.

FYI - My car is a '95 325i and the part# matches yours above.

Also, crash991, did you have any trouble as a result of not "coding" your module by BMW? Thanks!

[FIX]

Just tried the battery disconnect a few hous ago and I have the ice cold A/C I remember having. I did have the unit out of the car overnight, so it was disconnected from power for about 16 hours. We'll see how long this lasts. I didn't try the bench testing since the replacement part is $25 used.

[uberstout]

i have the same problem as well (94 325is) I just had my entire a/c system replaced, other than the control module. my battery died on me while i was listening to music outside(dumb i know) and the module started the light staying on business after that. the only difference in my case is that now my battery keeps dying. I wondered if there was any way the rear window defroster would keep drawing power if the module was telling it to after the car is off. gonna go try the ground fix right now! Also, does anyone have experience replacing passenger side window regulators on a 94 325is?

[FIX]

Uberstout, I don't think it's the defrost draining your battery since the A/C and defrost control module is wired to receive power only after the key is in the on position. Sounds more like an aftereffect of your radio draining the battery the first time it died. I'd have the battery checked by one of the national auto parts chains, they'll do it for free. It may just need to be recharged or it could be time to replace if it's more than a couple of years old. You might want to check the cells for water level too, they might be low or dry.

As an update, my A/C is still going strong in the oppressive Atlanta heat and I've done nothing else to it since my last post. I drive 70 miles a day, 5 days a week in terrible traffic and run the A/C all the time... it's been flawless!

Also, when I had the A/C control module out of my car, I took it apart and noticed a fair amount of loose crud inside the enclosure... not sure how it all got there, but I blew it all out thinking that the loose stuff might have been causing a weak short in there. However, the control module was also out of my car for about 16 hours, so maybe the key is to disconnect it for a longer period of time.

I hope this works for you too. If not, you can easily find a used module on e-bay for about $25, last time I checked. Sucks that you replaced all of your other A/C equipment already though, because this is such a quick and easy fix.

Sorry, I don't know anything about the window regulator, but good luck with that!