Mercedes S320 1995:
Cold air coming out of the heater vents !! Here is the background, originally I had a problem
with passenger side vent, belowing cold air when the heater was turned on, at anyhigh tempsetting,
but the driver side was OK (although not as warm as it supposed to be). So I discussed
this by a mechanic friend, he told me to replace the heater contol valve.
Over the weekend I purchase a used one from wrecking yard, and the sales guy tested
the part, to be OK, before I bought it (I am not sure what he tested for, seemsed like he was using
an ohm meter). Anyway after I installed this used contol valve, the problem got worse, and
now when the heater is on, I am getting cold air from the vents.

Could someone help?
Thanks
KT

 

duo valve.

replace it

 

Thanks SleepWalker,
Could you provide more detail, where the Duo valve is located on S320, and what does it look like? Do you recommend to repalce with anew one? or used one should be OK too? and how to test a used one, if I decide to buy a used one?
Regards
KT

 

Sorry to pick up an old thread, but I have the same vehicle with the same problem. Was this ever resolved?

My first post. Thanks for any advice!

Art