My wife and I love our 1986 420 SEL, but the A/C won't cool it. I have been going crazy trying to make my center vents work with my mechanic for two weeks. Back to the dealer twice for parts, one switchover unit and the second trip for heater elements. Now we've got complete vacuum but still the center vents won't open up. My mechanic now tells me I need a new pushbutton climate control unit. Problem is I just purchased and put in a rebuilt pushbutton climate control unit from "Adsitco" a month ago.

Is there a definite way to find out if the pushbutton unit is the culprit?

Your advice will be much appreciated.

Chasing My Tail,
Dave

W-126, Right?
 

I assume that the system is fully charged and the compressor is coming on?

Have you checked the vacuum pot on the driver's side of the transmission hump inside the car? That's what opens the center vents. Also have you tested the pressure switch on top of the dryer/accumulator? If you bypass that switch and your vents open, it's defective.

The only other thing I can think of is the mechanical actuator in the dash.

"vacuum pot"
 

Scott, your giving me hope! What function does the vacuum pot serve? like a reservoir? Is it just under the drivers side transmission cover mat?

Thanks,
Dave