rcroasdale

Anyone know why my '09 CLS 550 blows really hot air and then changes to cold air or it will change from cold air to hot air from the rear a/c vents?

kirejo1965

Im experiencing the same issue.. i know that other similiar MB's car have a control valve that was updated to resolve this issue. Question to you: Does the rear HVAC screen lite up at the end of center console???

MJ50

moved to C219 forum...

unlukky

Search diverter valve.
Its under the plastic cover where your windshield wiper motor is.
About $35 DIY.

unlukky

Or something like that. A small valve controls that under the hood. Diverter valve or mixing valve or something like that.

rick hesek

Duo valve. When they fail, the symptoms are as you have described.
P/N 211 832 0584. $55 at the dealer. They will charge another $400 to install it.