The center vent blues...

[1980sd]

1980 300SD

I started work on my ACC today. Testing with the mity vac, looking at connections, etc...

I figured I'd start with the center vent and defrost pods. Testing revealed the defrost pod was kaput, the center vent pod was OK. Some poking around confirmed my suspicions. They are almost impossible to service without pulling the dash

I had the instrument cluster, glove box and center ACC panel out and it was impossible. No way I'm going through all the work to pull the dash...

Anyway, I decided to try pulling the drivers side defrost duct. It's held onto the center stack with flimsy staples and to the underside of the dash with metal tabs bent over.

I'm happy to report that it worked:



Out:



It was fiddly, but not really that hard!

This is what the factory setup looks like:



I also pulled the nozzle which is held on by 2 little metal clips.

The white pod is one of those double acting deals which controls the defrost flaps and the pink one is the center vent control. If the double acting pod craps out the center vent won't work

That's THREE vacuum connections to run two functions, one of which is redundant because there is a manual center vent cutoff.

Since my pink pod was working I just swapped it to the defrost position and I'm going to remove the automatic center vent flap.



Here's the center vent nozzle and register assembly:



The automatic flap:



Any input? I still need to check out the leg flap pod but if it's dead I'll probably just work around it.

I'm going to be using the semiservo for blower speed switching:



It works well for changing blower speed via the thumbwheel and the push buttons give some more control.

This weekend I plan on mapping the vacuum part of the push button assembly to see if I can get the defrost pot working when the defrost or bi-level switches are pressed. When the leg flaps are open it just pumps air into the doors which is weird...