Heating problems

[Denisl]

Hi my W211 270 CDI 2003 has developed a problem with the heating system, I can have the car as cold as I want but can seem to get it to blow hot air. tried with air con off and on no diff even on long journeys. Car out of warranty so no cheap fix available. Anyone got any idea?

 

[Carlo]

I've had a similar problem from a customers w211 320 CDI .
Replaced the Unit in the dash and the problem was solved.
Can't say that you're problem is the same.
Should get a read out with the Star.(stealers visit)

 

[Denisl]

W211 Heating

The unit seems to be working, all the buttons dial work, blow air etc.. Although the Aircon off button will now not go off (red light stays on) Anyone out there with any advice? Having read the threads thought it may be the duovalve, has anyone changed this on a W211?

Thanks in advance

Denis

 

[zerocool]

yeah its the duo valve for sure I have changed loads,its a bitch of a job too.
the valve in question is directly under the brake master cylinder,and has 3 coolant hoses going into it.normally takes me about an hour to change

 

[Harry]

does the air con off button flash on and offf when you try and switch it onto a/c then go off because mine is currently doing this.

 

[Denisl]

W211 Heating

Hi Harry,

Yeah the AirCon off button flashes 3 or 4 times then stays on! Not sure what the problem is but think that it Air con may need regassed and it appears my duovalve maybe faulty. Need to go to independent garage for estimate.

How did you get on with yours?

Denis

 

[zerocool]

no hot air is definatly the duo valve in my experience,and the system will log a fault for this,possibly why your aircon button is flashing.

 

[Denisl]

cheers, It's going into for diagnosis and hopefully repair next Wed.

i will post findings

Denis

 

[Harry]

i've not got around to fixing mine yet but the flashing of the A/C button when you try and go into air con mode seems to be identical between yours and mine however i have no problems with the heater working, it works fine as does the temperature control, i just cant get out of economy mode.

i'm due a service in about a months time so will get it looked at then. i have a feeling it needs regassing.

 

[Denisl]

Took car in today, problem not solved, apparently the compressor is continually on and will not switch off. All other heating functions are working and the diagnistic software confirms no malfunctions! It's going in for further investigation next week. does anyone have any suggestions?

 

[Denisl]

Diagnosis was the duovalve, now replaced and heating is now working as it should. Thanks for all the help. good call Zerocool thanks

Denis

 

[ritchie]

According to MB if refrigerant is low the system will switch off to protect the compressor, indicated by a flashing ACOff button. This happened to me as I drove away from the dealer. A re-gas and laptop re-set by MB solved the cold air issue, it now blows no hot air! I'll suggest the duovalve to my perplexed MB tech...

 

[zerocool]

duovalves are common on 211 E class models,I have painfully changed a lot lately,they are also very easy to diagnose

 

[Dieselman]

Diagnosis was the duovalve, now replaced and heating is now working as it should. Thanks for all the help. good call Zerocool thanks

Denis

Very interesting.
Thanks for letting us know Denis

 

[ritchie]

Here's a good one...my local MB dealer also diagnosed the duovalve and insists that replacing it involves removing the wiper assembly & bleeding the brakes. This will take 4.5 hours and cost £656!! Now that really is a lot of hot air...

 

[BlackC55]

Thats is a load of BS. The proper instruction say you have to remove the master cylinder but you don't have to in reality. Its a awkward job but possible.

Have done about 20 to date.

 

[ritchie]

BlackC55 & Zerocool are both quite correct (thanks!) The supplying dealer sorted the duovalve under warranty, 1.5 hours, not the 4.5 quoted by MBHampstead. It's worth asking...

 

[BAABU]

I'm new to this forum and I can say I have a W211 E220 CDi and I've got freezing air con but no hot air. My mechanic said the same thing, it's the duovalve. However, he said it's an hour's job thankfully ! You know what dealer's are like.

I guess with the cold summer I'll need some kind of heating !

Nevertheless, what a fantastic forum. Thanks to all for their bit.

 

[zerocool]

an hour,I have done dozens of these,and an hour is really pushing it,but if you can nail him on an hours labour regardless of how long it takes hime,then tear his hand off,I would want at least 2-3 hours to change one,just because it is a knuckle skinning job

 

[BAABU]

Zerocool, an hour was just verbal but he wanted 2 hours labour just in case !