I've been trying to get this climate control problem fixed. replaced the blower so at least that works.
but then the ac wouldn't work, and with the heat off the gates in the duct seemed to be staying open and hot air would continually flow (convection, no fan).
so I also replaced the temp selector switch, & found that the thermo-couple was clogged with dust so cleaned that out.

now it seems to work well at first. when you start the car with the climate control off the gates are closed, you can run the a/c or just the fan, and the heat and defrost work. the problem is that when the car heats up and the thermostat trips it to shut down the heat or turn on the a/c it doesn't.

you can tell when the thermostat trips because a rattling noise(sounds like maybe a seliniod is strobing open and closed)can be heard and you can see the linkage coming from the vacuum pot trying to release, but it only moves a little and kinda shifts back and forth. if I disconect the vacuum line from the pot the heat resets down to a/c and the gates to the heatercore shut. I can hook the line back up and everything works fine again until time to switch back down off of heat, then the whole thing repeats.

so it seems obvious I have some sort of problem dumping exsess vacuum.

the first thing that comes to mind is that a selinioid actuated dump valve isn't working.

so here are the questions-
1. can I get this valve by itself or do I need to buy the whole control unit?
2. is there something else I should check (besides the valve), that could be causeing the valve to make that rattle noise and not dump vacuum.