• The Forums are now open to new registrations, adverts are also being de-tuned.

School me on W219/W211 cabin temp sensors

clk208

MB Enthusiast
Joined
Feb 14, 2009
Messages
1,282
Location
NW
Car
CLS
Got a strange climate issue at the moment on my CLS where the drivers side is a few degrees warmer than the passenger side. 2 zone facelift style climate.

I’ve had the cover off the temp sensor down near the steering wheel and there is nothing behind so assume it’s slipped down behind the dash- I’ve read about this. The cover has some plastic sheet over the inside which wouldn’t have allowed airflow which is very odd. See photo.

My car the last 9 years and never noticed this climate issue before.
 

Attachments

  • 5ADF0185-550A-4B46-9B17-814F54AA5E55.jpeg
    5ADF0185-550A-4B46-9B17-814F54AA5E55.jpeg
    149.3 KB · Views: 12
Forgot to say..

Anyone know where the other cabin sensors are located? Was going to give them all a clean.
 
The temp being unbalanced on each side can also be a failing duo valve (aka Heater Control Valve). Was on my W219 and was fixed by a new one, but you can also try repairing them. Plenty of Youtube videos

Good write up
 
The temp being unbalanced on each side can also be a failing duo valve (aka Heater Control Valve). Was on my W219 and was fixed by a new one, but you can also try repairing them. Plenty of Youtube videos

Good write up
I did wonder about the duo valve.

Thing is the temp controls still function and if I set passenger to 21 and drivers side to 18 I get the same temp out of both sides. Botha sides also respond to lowering or raising the temp so I was doubtful of duo valve but happy to be corrected?
 
The issue with the duo valve is that access is hindered for RHD vehicles. I replaced mine recently after a couple of years of procrastinating for someone to do the job. The duo valve cost £15 and the labour etc £414, because the servo has to be removed and the brakes bled.

It now means, however, that I no longer have the hottest air venting from the rear and making the children feel sick and making the front occupants very uncomfortable. Ironically, I opted to get it done before this year's drive to the South of France (along with a couple of other jobs)... which was cancelled shortly thereafter due to the mandatory quarantine for travellers. Still, it's nice to have cool cabin on our soujourn to rainy Glasgow!
 
Could still be the duo valve - they crud up inside and it restricts the movement of the valve, so it could be moving within a more limited range for one side. A bit of a pain to get to but not too expensive for the part. I would change it as they are a known problem when they age and then you are confident that you have eliminated that as a possible issue and you can start going down the rabbit hole of electronic control failures.
 
The issue with the duo valve is that access is hindered for RHD vehicles. I replaced mine recently after a couple of years of procrastinating for someone to do the job. The duo valve cost £15 and the labour etc £414, because the servo has to be removed and the brakes bled.

It now means, however, that I no longer have the hottest air venting from the rear and making the children feel sick and making the front occupants very uncomfortable. Ironically, I opted to get it done before this year's drive to the South of France (along with a couple of other jobs)... which was cancelled shortly thereafter due to the mandatory quarantine for travellers. Still, it's nice to have cool cabin on our soujourn to rainy Glasgow!
The W219 has it in the middle of the scuttle cavity below the wiper setup so easier to get to - relatively - or it was on mine
 
water changeover valve (not anymore exactly duovalve in these) usually cause heat problems in between front/rear ... when I had problems driver <> passenger side in my C219, it was due to almost empty ac coolant. First there was problem gettin cold in drivers side, then there was whining noise coming behind center concole. AC system was almost totally empty.
 
water changeover valve (not anymore exactly duovalve in these) usually cause heat problems in between front/rear ... when I had problems driver <> passenger side in my C219, it was due to almost empty ac coolant. First there was problem gettin cold in drivers side, then there was whining noise coming behind center concole. AC system was almost totally empty.
Cooling is on the weak side at the moment now you mention it and was overwhelmed by hot weather a few weeks ago.
 

Users who are viewing this thread

Back
Top Bottom