mercedes cdi c220

[ukace58]

hi can anyone help , my 2004 c220 will only blow warm air at low fan settings if I turn it up its just blows cold air, I have changed the thermostat and flushed the cooling system replacing the coolant.
just need to no are there any valves or pumps that cause this , the car runs fine temp all ways around about 80 .
cheer Steve

 

[mercedes13156]

That could be the duo-valve. it sits in the driver's side of the engine bay in front of the brake master cylinder, with two smallish pipes at the front. I can't remember its actual function, but on a previous C Class, the heating went wonky and I was advised to clean the duo-valve in case some previous application of Radweld, or similar sealing compound had started to jam it up. That was indeed the case and once it was cleaned and put back together, (a bit of a fiddly job if I recall), it all worked wonderfully again.

Once I had been told of the potential problem, I gave it a couple of donks with the back end of a large spanner. That improved things a bit and told me that I was on the right track. Stripping it and rebuilding it solved it for me. Just don't rip it out and strip it down without being sure you've got the true culprit.

 

[alexanderfoti]

No duovalve on the 203. Its probably a flap problem. Does the car click from the dashboard when you turn the ignition off

 

[mercedes13156]

No duovalve on the 203. Its probably a flap problem. Does the car click from the dashboard when you turn the ignition off

Thinking about it, it must have been on my old W202, not the 203. Please disregard my previous post.

 

[ukace58]

thanks guys sorted , was a bad airlock