Spent some time with the car installing side-markers, fixing my power seats and investigating the climate control.

The auto/auto reset test gives me ~20 flashes on startup. The switches still run the flapper servos so I'm thinking the unit is okay after all. I still get no fan no matter what I do. Maybe I was hearing things when I thought the lowest setting did something. Could have been a flapper servo...

I realized that the AC *only* turns itself on when I have the vents set to defrost. which seems normal for maximum evaporation now that I think about it. It is at least predictable so I do not think it is a symptom of a failing ECC unit.

I tried disconnecting the cabin sensor from behind. That resets the module but doesn't give me any fan.

I poked around behind the glovebox and could not narrow down what plug actually goes to the fan. I managed to unhook the big colorful connector block and kill the car and set my ABS/TRACS light in the process (that's another issue for discussion).

If I could find the plug, I could try some direct 12-volt power. I'll give the YouTube video another go. The guy had everything disconnected already which was not helpful.

I'm still a bit flumoxed that the fan came on by itself and started blowing on Saturday (without warning) but has been dead before and since.

Does a bad power stage act like that?