W211 heating issues

[Droctogon]

Hello all, I was wondering if someone out there has any guidance on this little problem for me?
I've recently bought a 2004 e270 w211 and since the purchase I've only been able to draw hot air through the vents on the passenger side. After some searching on here I learned of the common issues with the duo valve, which as of an hour ago has just been changed for new. Tricky but I got there, but with zero results. Still blows cold on the drivers side and now out of ideas.

I have however noticed that the control panel inside the car seems to have an issue, I.e. The rest button on the right hand side of the panel (automatic air distribution and airflow) never illuminates when pressed, as this is also the temperature selector I'm wondering if these ever go faulty and/ or a blown fuse, although highly unlikely I suppose since the rest of the panel works fine.

Out of ideas and starting to lose patience every morning waiting 30 minutes for the drivers side to defrost so if anyone has any pointers then I'm all ears

 

[television]

Rather than chase this fault around it would be far quicker to get a STAR read out from an indie, yes it usually is the change over valve.

 

[Droctogon]

Thanks, as though you read my mind its booked in tomorrow for the diagnostics so fingers crossed it comes with the problem.

 

[Droctogon]

Well, the diagnostics came back reporting no issues at all.

So... the duo valve works, the electrics are all fine and the fan is obviously working even if it is blowing only cold air.

My last guess would be either a defective motor or broken linkage, both of which require the dash removed before final diagnosis.

Have I missed anything out here before I start ripping the dash out?

 

[television]

Was this done on STAR

 

[Droctogon]

Yes it was, conducted by a Mercedes specialist.

 

[Corned]

It will be the change over valve. When mine went there were no fault codes logged either.

Bastard of a job DIY to do, but not impossible.

 

[television]

It will be the change over valve. When mine went there were no fault codes logged either.

Bastard of a job DIY to do, but not impossible.

He has fitted one ??

 

[Droctogon]

Cheers Corned but the heating valve was the first thing I replaced with new and no results. (mentioned in my first post) Assuming we are talking about the same unit here?

http://i6.photobucket.com/albums/y205/w211_ryda/oldvalve2.jpg

your right, was a very fiddly little job since the unit no longer sits directly onto the inlet pipes on the bulkhead, as on earlier models, but with the help of some extra piping, sits directly under the brake servo. Was a nightmare to get to especially with large hands but made a very handy little tool that served its purpose well.

 

[television]

That is the one under the steering column

 

[Droctogon]

Hmmm, not that I'm questioning your info but mines was located here:

http://i6.photobucket.com/albums/y205/w211_ryda/DSC01276.jpg

Although as I mentioned earlier the unit itself was just away from this location under the brake servo.

 

[Corned]

Is yours a LHD?

Anyway, if that's new then there should be no issue with it. You did plug the electrical connections back in again though, didn't you?

The other option is sticking distribution flaps in the dashboard/main heater box.

Or, as you say, it is not unknown for the control panels themselves to fail. I'm pretty sure we've had that one before on here. Might be worth trying to get hold of one on a sale or return basis and giving that a try. It would be easier to change that than to demolish the dashboard (or the brakes again!).

 

[Corned]

Scratch what I said above.

Yours used to be under the master cylinder, but is now under the wiper linkages, as per LHD versions?

In which case, it is now sitting considerably higher than it did before. I wonder if it is air locked as it won't automatically bleed through the system - as it would have done in the original location?

 

[Droctogon]

its a RHD,

apologies, possibly these photos I'm passing over are a little confusing as they are taken from the installation PDF I used to install the new valve from what looks like a LHD version. my bad on that one. :Oops:

yes, I was very careful when it came to removing and reinstating the electrical connection.

As confusing as the picture is it seems, on my car the duo valve was located very close to where you see the one on the bulkhead photo but seated directly under the brake servo unit, as is the replacement valve.

 

[Corned]

Right - I know where you're coming from now! We should be able to eliminate the valve from our enquiries.

The REST function. This only works properly once the coolant has some temperature in it. When the car is full warmed up, will the REST function still not work properly?

If it will not, then the replacement control panel looks like the way to go - see my post above for details. Also search on here for "faulty heater control panel" or words like that, as I'm sure we're had that before.

 

[Corned]

I should also add that the REST function places quite a load on the battery, as it keeps some coolant in circulation and drives the blowers, etc, albeit at a reduced flow rate.

The red indicator light should be constant while the fuction is working, but will start to flash to warn that it will soon be shutting down. This will be either because there is no temperature left in the coolant, or the battery is taking a hammering.

So to test it properly, you will need hot coolant and a decent charge in your battery.

 

[Droctogon]

Well :Oops: like a complete novice I did mention the fact that the "rest" function was not illuminating when pressed to the specialist this morning and he modestly pointed out the reason for that. i.e. he turned the car off and hey presto guess what lit up when pressed.

so... with my stupidity in mind there is no issue with the control panel whatsoever.

 

[television]

If this was a control problem it would come up on STAR, the faulty change over valve does

 

[Corned]

Lol! Back to stuck distribution flaps then?

P.S. My dead change over valve did not throw and fault codes.

 

[television]

Lol! Back to stuck distribution flaps then?

P.S. My dead change over valve did not throw and fault codes.

It did on my 230 that uses the same valve.