Climate Control FAILURE - United Bimmer Community

**BostonGreen318** · 12-12-2010, 03:04 PM

I’ve been experiencing ongoing climate control failure w/ the analog unit in my 1994 e36. These are the symptoms:

A/C, defrost, and recycle lights intermittently and randomly switch on and off.
There are times when no air flows from top vents on any of the 4 speeds.
Sometimes unit shows no response whether pressing buttons or turning the
dials.

The following have already been replaced:

Climate control unit
Blower resistor
All fuses

Thanks in advance for any help.

Big Evil · 12-16-2010, 03:15 PM

I'd be looking for bad grounds and/or loose connections

**3050rpm** · 12-16-2010, 10:15 PM

Check this site out and see if it helps http://www.macadamizer.com/bmwfix.html

**BostonGreen318** · 02-25-2011, 09:51 AM

First off, thanks 3050rpm for the suggested link. The only problem is that the CCU in the article is the digital version - I’ve got the older analog.

As of now, the climate control unit is no longer operating at all unless the battery is disconnected and then reconnected. This suggests that the issue is an electrical complication caused by bad ground wiring. Is this a reasonable assumption?

Being a layman, I’m not altogether familiar with the ground wiring of an automobile. According to the Bentley service manual (p. 100-13), there are 3 main ground points. The first is the main ground for the engine management system (positioned somewhere in the right rear of the engine compartment), the second is the main ground for the ignition coils (underneath the diagnostic connector), and the third is the main chassis ground (in the left front of engine compartment, behind left set of headlights).

My questions are as follows:

1. I believe there are other ground wires for other systems but where are their locations exactly?

2. The manual suggests wires “sometimes break internally or in areas not easily visible.” How does one replace such wires?

3. I’ve been unable to locate reference numbers for replacement wires. How does one purchase replacement ground wiring?

**3050rpm** · 02-27-2011, 09:03 AM

Sorry to hear of the continuing frustrations. In light of what you describe, I wish I had more than a tidbit to offer, that is I believe grounding wires are fairly generic, I think generally of a braided or large gauge variety. Any auto parts shop should be able to help you out. Of course, the problem is finding where the problem lies...

**BostonGreen318** · 02-27-2011, 05:06 PM

Thanks, 3050rpm. That was what I was suspecting. Just not sure what gauge wire is required. I've recently read about an "engine ground strap" and I'm not too sure what that means. Anybody familiar with this and where I'd find it? I'm pretty anxious at this point after switching on the highbeams the other night and experiencing a near stall while accelerating. Seems like it might all tie together somehow.

**3050rpm** · 02-27-2011, 10:28 PM

Right, there is an engine ground strap. I think it is a flat braided strap, running from the alternator to the frame. I think you're on the right track, but doublecheck what I've passed on. You might find some assistance in terms of getting a part number and diagrams by going to www.realoem.com/bmw.