E320 cdi (w211) help needed please


Mar 18, 2008
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I am hoping that someone can help me with a problem that I have with an 2003 E320 CDI. Basically the problem is that the heater is not producing any heat, you can only get cold air even if it turned up to max on the 2 zone climate control. It has been looked at but they can't seem to get to the bottom of the problem. I have been told that all the pipes running to the heater matrix are hot as they should be and also the pipe coming from the heater matrix back to the engine is also hot but we still can not even get slightly warm air to come through the vents on either side.

At the moment my mechanic thinks it may be the heater control valves but as this is listed as a 7 hr job and also involves removing the fusebox and ECU's to get to it he is reluctant to take it all to pieces as once he does he has no way of testing the part as obviously the car can't be powered up without the fuse box and ECU's on. I really can't afford to send the car to Merc so if any of you knowledgable and merc experienced people out there could point me and my mechanic in the right direction it would be greatly appreciated.

Thanks in advance :)


Always remembered RIP
Mar 14, 2005
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Your Mercedes
2002 SL500, 216 CL500, all fully loaded
Hello Benz lady,,all you need to do is to give the duo valve a bang with a small hammer of iron bar and it could come back to life,,it is not 7 hours work though,,fiddly yes.

you also have a circulation pump,,is that running

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