HVAC is not working correctly.

I have tested all vacuum pods and everything holds vacuum and actuates as it should. Pulled out the solenoids (6 on the '82) and tested them on the bench. All work as expected. Tested the 2 position switch that drives the center vent and it works as expected.

With the controller connected I keep getting different results and can't seem to reproduce any specific issues. Fan works when the slider is not in OFF position based on the number and goes to full blast on the defrost mode, so fan works as expected.

In no situation can I get the center vent to open at all. Heat is off sometimes and on sometimes. Recirculate flap seems to work as expected in some modes, but inconsistent.

I actually pulled the wiring off the solenoids to see what the controller was doing in each mode. This is where I could go back and get a different result on something that didn't make sense to me.

Am I nuts or does it seem like I need a new control head? The thing is so simple that I have a hard time believing it can be the problem but I don't know what else it could be. I have pulled it apart to clean (deOxIt) and inspect. All looks good and tests as it should as far as I can with a multimeter.

Any ideas what to try next short of just getting a new controller?

Thanks.

 

Try verifying all of your solenoids do not leak vacuum. They are getting really old and are starting to fail more often even though they may activate, they might not hold vacuum properly. 2 of mine just died on my 81.

You could clean the contacts in the head unit for the sliders as well as those are what controls the solenoids activating.

Other than that, there really isn't much to go wrong in our systems other than dirty connections.

best of luck

 

Thanks Blake

I put a vac on each solenoid then hit it with 12 volts and it released the vac. Is that enough of a test or should I do something in addition.

I agree that the system is pretty simple and I can't imagine what else could be going wrong.

 

You're welcome

That sounds like they are working then. Some of mine don't actuate and I hear a constant vacuum leak from them, like they are stuck half open. C'est la vie...

Your 82 has the same auto climate control head as my 81 if it has 6 valves, so check the PCB inside of the unit for burned traces and clean it up with some contact cleaner. They react pretty well to it normally.