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1997 C230 185K (Sold) 1999 C280 Sport 122K (Sold) 2007 C230 105K
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32 Posts
Discussion Starter #1 (Edited)
Hello Good people!

Recently I purchased a 1999 C280 Sport with 122K mi.
It came with an A/C problem and I just want to describe symptoms for your feedback. As always your feedback is very much appreciated.

1. When the car starts initially, 8/10 times the air works fine, blows and blows cold then stops.

2. It randomly comes back on and may come back on (when turned on to hi) and blow lightly as though it was not turned to full. Sometimes its turned to lowest blow setting and blows as though it is turned to full setting.

3. The dash vent blows always, whether the CCU is set to "feet and windshield" or not , the dash vents blow at all times, the floor vents don't always blow, they go on and off. Are these issues related.

Any input will be greatly appreciated. For 1 and 2 I am guessing the regulator? For 3 the CCU or vacuum hoses? Please advise.

Thanks.
 

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1999 C280 210k miles
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200 Posts
The vent problem may be a vacuum issue like a cracked line or fitting. I've heard of lots of issues with hot / warm air always coming from the side vents or always from the center vents - this is a duovalve sticking problem - search this forum on douvalve to learn how to disassemble and clean it. I did this and got things sorted out.

The intermittant cool air could be the evap temp sensor which is accessible behind a panel inthe driver side foot-well. I had similar symptoms and this did the trick.
2108300772 A/C Evaporator Temperature Sensor $37.76
at Autohaus AZ
 

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1995 C220
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33 Posts
Intermittent Air

If the air is not changing when you push the different motor speeds and it stays on after you shut the key off for about five seconds...then it is most likely the regulator...and that is probably junk because there has been water coming in to the passenger compartment via the dash. Before I replace the regulator I would clean out the drains to ensure that you do not get water in there again...I put a thread in tonight explaining the whole process...good luck...
 
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