A friend of mine just got a nice 88 CSi with rear A/C. The rear A/C blows cold, but we can not get cold air from the front vents. Any tips on where to start looking?
Thanks

sounds like it could be the vacuum seals that seal off the vents when you close them. Do the front vents blow at all?

Yep, lots of air, all not-cooled.

OK, I'm pretty sure that it is the vacuum seal. I am by no stretch an expert on such things, but I'm pretty sure that there is an internal type "door" that opens and closes via the vacuum depending on whether or not you use the blower or the ac. Unfortunately I think that the dash has to be removed to find the problem. Have you tried going to bigcoupe.com to post this question? There are a lot of really informed mechanic types who lurk there...nice chaps too.

The other only thing that I could think of is there may be two ac motors in the car, one that drives the rear and one that drives the front. If this is the case then the front motor might be shot...but I'm pretty sure that there is only one condensor

Hi I am having the same problem with my 1989 635. I have not been able to resolve the prolem wither. I hope someone can help you. I will be watching this string.

In the earlier cars the fresh air "Door" is directly controlled by the center slider. In the later cars a stepper motor controls this door to ensure that it is closed when the A/C is on. To test the stepper motor, turn the key on and move the center slider. You should hear it open and close, leave it open. Press the A/C button and you should hear it close, but if it didn't this would just make the A/C airflow weak.

Yes, there are two blowers (3 if you count the heater blower), as well as 2 evaporators, 2 expansion valves and 2 temperature regulators. The two systems are basically separate except for a shared compressor.

Download your free ETM and go through the A/C troubleshooting charts to eliminate the temp. reg. and the evaporator temp. sensor, etc. as problems. http://wedophones.com/BMWManualsLead.htm

I have the same problem with my 89 changed almost everypart still no good

Check out this post:

http://bigcoupe.com/phpBB2/viewtopic.php?t=4618