My 2000 CLK430's air distribution controls, which are supposed to direct air up to the windshield, down to the floor, or forward to the occupants, do not work anymore. Airflow doesn't change no matter how I set them. This is especially odd since it's true for both the passenger and driver side controls, which are independent of each other. However, the Defrost button correctly directs air up to the windshield so it seems that mechanically things are fine. And everything else - air volume, temperature, recirculation, etc. - work fine.

Any ideas on what the problem might be and how to fix it?

Many thanks!
Pete

 

I'm going through the same thing right now and I can't figure it out. I know that there are vacuum actuators and I know that you can put the system into "diagnostic mode", but all I got from that was what I already knew (air direction is not happening).

Hopefully someone will chime in who's been through this already, because it's a real PITA.

 

I thought of the vacuum line issue but since the defrost button does redirect the flow I'm thinking it must be something else.

 

Yeah. That means we have separate issues.

 

I was getting ready to take the whole of the ventilation and heating system apart, ( a massive and complicated job BTW), when I changed the cabin air filter. It worked much better afterwards and dead cheap to fix.

 

I've replaced my blower motor and my cabin filter. Still no luck.