W209 CLK blows cold when cornering

[ollya]

Hi,
My 2003 W209 CLK 320 heater blows cold air into the cabin when I go round corners. Any ideas please? I take a route to work with lots of bends and as it's starting to get chilly in the mornings I'd really like to put a stop to it.

Thanks Oliver

 

[Ted]

Is the radiator/header tank topped up?

 

[martyz]

Sounds like a faulty duo valve for heat control.