Climate Control - No activity

[littlerobot]

1984 300D Turbo diesel

I recently replaced the ignition, instrument cluster, and pulled out the old stereo (didn't replace it, just threw the non-functioning one out). Now I cannot get any activity from my climate control unit. The buttons don't do anything, and no activity from the blower motor. I happened to have another CCU that I know works, so I popped it in and still nothing. I check the fuse and it's fine.

I can tell you that the sensor that goes from the CCU to the auto-climate thingy on the dash (the little black square in the center of your dash) is unplugged, but I thought that only worked when the CCU was set to "auto" climate control.

I know it's not the CCU itself, which leaves the blower motor and possibly the ignition, right? How can I find out if power is actually making it to the CCU?

Or am I missing something else completely?

I did pull a vacuum on the Climate system, which it held well, so Vac issues are off the table I think....