Neither the heat nor the air conditioning works in my 1995 S500. The clutch on the a/c compressor does engage. Does this mean that the Climate control unit has gone bad? The heat and air stopped working in the rear of the car some time ago. Now there is no air or heat in the front. If it is the control unit, how difficult is it to replace?

Hi there:

I am not sure which control unit you have. Do you have the BIG LCD display unit or the older style unit where it is seperated into 3 panels with a turn wheel on each.

Does your unit come on? I mean do you have the red lights when u press the buttons? Does it seems to be working?

If the unit seems to be working, since you said no air, I assume you mean no air blowing out. Did you check the blower and the clower regulator? the blower regulator is a common fail item.

Also if the unit is working, u can run diagnostic tests and get DTC codes to find out what went wrong. Have you read "Jimf" web site? He have millions of information regarding S500, a C140 but. Its almost the same as W140 so not to worry. Let me try digging up his address...

found it..

http://pages.prodigy.net/jforgione/MB_S500.html

goto point 15.

I also recommend you take a look at his cool harness. Its a easy plug-n-play to keep the engine cool.... needed on these big 140 if u use your car in a hot country.

My unit has the two separate controls with the wheels that you roll to adjust the temp on the passenger and driver sides. I'm sorry I was misunderstood, but it does blow air just not at the correct temperature. The air is neither heated nor cooled.

were you able to run the tests? results?? please post them.

I'm also having the same issue with my car. When I ran the test, it did not come back with any error codes, just the features. Is there a common part that usually goes bad first?

No I haven't repaired it yet. I don't want to spend the big bucks on the climate control until I'm absolutely sure it's the climate control.