Thanks for your replies. I couldn't find what looked like a HVAC fan connector near the brake booster or anywhere near, and my car doesn't appear to have the box as shown in the post #4 photo.

So I decided to remove the fan switch and CCU (with all the pushbuttons and temperature control.) The plastic trim panels surrounding these began cracking a few years ago. I may have made it worse, but I can probably make at least a partial repair with superglue and epoxy. I don't know if replacements are available, but I'll look around.

Once I got the fan switch and CCU out and electrically disconnected I turned on the key and no fans came on. So I switched off the ignition, replaced the #2 fuse and the aux. electric cooling fans remained off, so I should be able to drive the car, at least for short tripos.

The CCU has two ten pin connectors so I attached each one separately and no aux. fan with the ignition switch on, but they came on with both connected, ignition on. With the CCU electrically isolated, connecting the HVAC fan switch had no effect at any position.

I removed the bottom cover from the CCU, which exposed the bottom of the circuit board. It looks brand new.

Since the buttons don't work I figure the CCU is not getting power. I need to study the wiring diagrams I have, and see if I can figure anything out.

Does anyone know if the CCU is reparable?

In the meantime anyone familiar with these 80s-90s HVAC systems, any model, please chime in with any thoughts you might have.

Duke