Rear Air & Centre tunnel VERY Hot

[S350L]

Hi Guys

Yet another problem with my aging 2011 W221.

The centre tunnel gets very hot with very hot air coming out of the rear air vents. The HOT air does get cooler the slower i drive.

Any ideas please

 

[KillerHERTZ]

Heat shielding above the exhaust come off/removed and never reinstalled?

 

[S350L]

Thank you for your reply. Would that cause hot air to come out of the rear vent regardless of what temp I set it at

 

[Londonscottish]

Thank you for your reply. Would that cause hot air to come out of the rear vent regardless of what temp I set it at

If the rear passengers have a separate temperature control the valve could be faulty. It's somewhere behind the sash on some Mercs I think.

 

[Stratman]

Like KillerHERTZ my first thought was 'exhaust shield'. If there's enough heat to make the tunnel very hot there could easily be enough heat soak to affect the ventilation air temperature, as the ducts run along it.

 

[S350L]

Thank you.
I have seen some posts about some sort of valve. could this not be the case?

 

[S350L]

Extra info.
I dont think it's a heat shield as it only it only gets hot when the a/c is on

 

[ivan1983]

On the w140 the pump and I think duo valve for the rear ventilation are under the front driver side wheel arch. Could be the same on the w221
My problem was the opposite, cold air unless I revved the engine. New motor sorted it.

If you warm the car by letting it idle whilst parked up and the rear doesn't get hot but it gets hot if you prod the throttle a few times I would say it's related to the rear pump / duo valve.

When I had the issue on the w140 there was very little information on the internet about the rear hvac