Q&A

 Master

I like your style, Dude.

We have some good Chevy techs on the site, hopefully they will have some info.

I checked and there is a technical service bulletin: #46-12-02 It refers to a "fix" for some of the problems with these units. I have no idea how well this works, but hope it helps. Here is what is says:
Condition:
a/c control head flashes, performs erratically or malfunctions.
Cause:
light surface corrosion on the control head terminals.
Correction:
remove the a/c control head and while holding the unit with the terminal
cavity down (toward the floor) so no particles will fall inside on the circuit
boards, polish the terminals on both sides of the cavity with a lead pencil pink
eraser. do not use an ink eraser or other abrasive such as a small wire brush
or sandpaper, etc. doing so will remove the terminal coating and degrade the
contact surface.
**performing this procedure, in many cases, will make replacing the control
head unnecessary.** using this procedure in conjunction with the a/c circuit
diagnosis found in the electrical diagnosis manual and especially before
replacing a control head for any reason is recommended.
after polishing the control head terminals, but before reconnecting, check for
proper terminal contact as described in the applicable electrical diagnosis
manual. if contact is good, apply dielectric grease (p/n 12345579) to the harness
connector terminals. please do not apply grease to the control head.
service parts information:
p/n description qty 12345579 dielectric grease from tube as needed
parts are currently available from gmspo.

 Rookie

Good questions, bretb! Used heat/ac controllers from junkyards are nonexistent, and those early digital contollers are notoriously problematic, so any one I get is suspect. And since I've got two such beasts, I'm considering a totally different way of controlling the heat/ac, maybe a simple custom control solution from a classic car catalog, JCWhitney, etc.? Any ideas? Thanks for responding! thedudeabides