Cabin temperature management

[Any_Name_You_Wish]

Sorry if this is in the wrong section.

Changing the temperature on the dash works for the passenger but is stuck on hot for the driver. It's driving me crazy!

Any Ideas?

(2007 w211)

 

[V6Matty]

I think that’s the duo valve that’s stuck/failing, if it is then afraid it’s a dash out job to replace. I could be wrong though so let’s see what others say