Heater question w211

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Maxngm

New Member
Joined
Oct 2, 2023
Messages
8
Location
Norwich
Car
E class
Hi, the heater in my e320 works up to a certain level, but the higher the level, the colder the air gets no matter what temperature the heater is set to.

So if its between 1 and 4 bars it's fine but if you keep increasing it, the temp will get lower. The pic attached is where the heat dies off.
Does anyone know why it's doing this? Coolant is fine.
 

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Very weird, can't remember similar problem... often W211 heater problems are due to water changeover valve malfunctioning. It is possible that it is jammed, and now when you increase air flow, heater matrix is not getting more coolant and thus colder air blowing... just a thought
 
It should be the duo valve, it’s a cheap part but just a bit of a pain to replace.
 
I think reading this I’ve got the start of similar symptoms , I’ve just ordered a duo valve for mine as well !
 
RHD car is PITA job... LHD remocing wiper machanism gives the space, though better do some wiretool to open locking. Also note that aux heater car water valve has an extra connection.
 
RHD car is PITA job... LHD remocing wiper machanism gives the space, though better do some wiretool to open locking. Also note that aux heater car water valve has an extra connection.
Yep I’d spotted the horror stories ! Thanks buddy :)
 

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