Hi,
I have replaced literally all the componenents in the climate control system inside the car. These include all the little vacuum motors for moving the various flaps etc., the vacuum switchover unit that resides behind the passenger air outlet, the push button control unit and the little potentiometer that lives up under the dashboard on top of the heater box.

My a/c will blow cold on some of the settings and I can get heat when I call for it. What I cannot get is the flaps that shut off the airflow to the windshield defroster nozzles to close when they should.

I have the MB climate control manual but it uses a lot of special tools for testing. Does anyone know how I can test the pushbutton box definitively. I may have gotten a dud when I replaced it. Right now I have the entire dashboard out because I'd like to solve this once and for all.

Any help appreciated as I have hundreds invested intrying to fix this system. At a minimum, does anyone know how to test the pushbutton box without the special MB "socket box"?

Thanks,

Jim

 

If I'm not completely mistaken, the windscreen nozzles never close completely to esure some air flow to the windscreen anytime. But may be I not quite right. But if you have the thing open you may see if they close to a certain extend, or if they do nothing then something seems to be wrong.

 

bamberger_1, The vacuum motor that controls the windshield nozzles is actually a two-stage motor. It has a long stroke that closes them almost all the way and a secondary stroke that closes them fully. How and/or when it decides when to use the long stroke and/or the short stroke is something I am not yet sure about. Either way, I'd be happy if it would just close them most of the way as failure to do so means that I never get enough air to the lower (leg-room) area.


Jim

 

At least on the W124, the windshield air nozzles never close completely.

Did you get a used PBC unit or rebuilt?

 

A rebuilt unit.