S212 centre only blowing hot

[Londonscottish]

Mods; to make this clearer, could you change the title to "S212 centre rear vent only blowing hot air". ta

I just noticed a post from Bolidemichel about a problem with the rear vent(s) in his S211 that were only blowing hot. He sorted it by replacing the duo valve under the scuttle.

My kids have started complaining about the same thing in my 212.

The symptoms are the the rear central vent is now always blowing hot no matter what temp is selected on the rear controls. Inspecting further, I can feel heat in the base of the central cubby hole and along the side of the console.

Anyone got an suggestions as how I should diagnose & fix and roughly how much it would cost?

Thanks

 

[Ta51]

Hi,
Did you manage to fix it?
I've got exactly the same issue with hot at the back and heat from centraland can't find any answers.

 

[MikeInWimbledon]

I had this problem recently with my new to me S211. The car hadn't done many miles over the previous year, so I suspect that things may have just "settled" in place.

The issue lasted for about a week, with heat coming out of the rear vents. (4 zone controls).

My simple approach was to fiddle with the air con controls front and back to try to get some movement into the valves again.

All I can say is that after a week or so, it all sorted itself out. Nothing more fundamental needed doing.

I have a track record of buying very low mileage or "deceased spec" cars which haven't been used much, so I'm used to the idea of lubricating hinges, opening / closing pano roofs, easing rear hatches etc etc simply because functions haven't been used for years.

One closing question: did anything change before you noticed the problem? Someone sat in the back for a change and fiddled with vents?

 

[Ta51]

I bought my 2010 mercedes s212 e350 cdi about a year ago and on the way back home, which was about 100 miles away, I noticed heat in the base of the central cubby hole and along the side of the console. But it was a very hot day, and I didn't really think about it much.
Then next day my wife noticed that the rear a/c is set to LOW temperature on display but only hot air coming out. I went to my mechanic, he run some diagnostic but nothing comes up, and he couldn't tell me what causing it without stripping and digging deeper which might cost god knows how much. I was wondering if there is anyone with same issue in w212 estate (s212) who knows what exactly could be the problem.
Thanks

 

[MikeInWimbledon]

So have you altered all the major air con controls to check that nothing is “stuck” in the wrong position.

If you have a heating control in the central console (storage box) has that been adjusted / fiddled with?

Opened & closed the vents on either side of the dashboard?

 

[Ta51]

Yes, I tried every possible setting, front, back, sides, open, closed , hot and cold. In every way warm air coming out from rear vents.

 

[MikeInWimbledon]

Yes, I tried every possible setting, front, back, sides, open, closed , hot and cold. In every way warm air coming out from rear vents.

Understood. I was asking if you’ve adjusted several times subsequently, to nudge jammed controls out of a stuck position. Like adjusting rear console temperatures to “normal” (call it 18) rather than “LOW” even though they were jammed and running hot.

It sounds daft but you’d be surprised how many people just leave air con stuck in the same position for years without ever adjusting position, and controls do get stuck.