W220 Front heater blowing cold

[kenmac]

Right this is an odd one, my front heater was blowing cold tonight even though it was on HI, but as it’s a LWB I’ve got rear heater controls & that one is blowing lovely & hot, so can’t work out why one blows cold & the other hot ???
Any clues please.

 

[ChrisHampshire]

Probably a fault with the front duo valve (which is located under the windscreen wipers). The rear heating has its own duo valve (located in the osf wheel arch), which is why they can be independently functioning/problematic.

 

[kenmac]

Probably a fault with the front duo valve (which is located under the windscreen wipers). The rear heating has its own duo valve (located in the osf wheel arch), which is why they can be independently functioning/problematic.

Cheers Chris
I'll have a look at that