MB 1990 300CE Automatic Air Conditioning Problem
 

My 1990 300CE puts out both cold and hot air at the same time. The hot air comes from the left and right side vents and on the left side of the center vent. Cold air comes out of the center vent in the middle. What could be causing this?

Someone told me that the board behind the AC controls is at fault.
If so, can reconditioned boards be bought?

Any help on this subject would be greatly appreciated!

go.dale@verizon.net

More likely, the blendor motors have failed. In my case, I disconnected the battery and reset my computer and it took care of it, but this is the exception...usually, a very expensive fix.

It could be anything from the duovalve unit malfunctioning to a bad a/c pushbutton assy. Have seen both of these components fail and cause this problem . You would have to get a electrical diagram and stsrt troubleshooting.:D

I think that 99% of Mercedes climate controls experience warmer air from the side (dash) vents with age. I believe it is a vacuum leak, or some sort of air leak.
If you do a search, you'll find information on this problem; it's been discussed several times.
Good luck!