Blend door actuator shaft does not move: both old and new actuators

[myf16]

My 1996 Explorer with manual temperature control is stuck on high heat. If I turn on the AC I can almost get it back to ambient temperature. It was working perfectly a couple weeks ago. It has never made noise.

I removed the blend door actuator (F57H-19E694-AA) and determined that its shaft does not move when I move the temperature control. So I bought a new one (F87H-19E694-AA and it looks the same). The shaft on the new one doesn't move either. I don't think power is getting to that connector.

******* Oops: My new actuator looks like it's for automatic temperature control. My bad. *********

I checked fuse 10 and all the other 7.5 amp fuses. There are small AC voltages on the pins of the unplugged connector, so I now think signal is getting to the connector. Maybe they are pulse width modulation signals? I have verified that the temperature control is just a 5k ohm rheostat, working correctly.

Measurement revealed that Fuse 10 was blown. I needed a magnifying glass to see it. The fuse blew again with no actuator box present. Looking at the wiring diagram, the other problem areas are the rear blower relay and the rear air control panel. The rear blower relay is one of the 6 small relays above the accelerator pedal. But which one? I can't find a diagram for that under-dash relay box anywhere.

What should I check next? Does the signal to the blend door actuator come from the rheostat or somewhere else?

Edit: Solved. Rear blower motor relay location?