1950 Mercury Heater Q's

[Sixseven]

Seeking clarification on the heater operation for this car. The heater switch, fan, plenum and heater core all appear factory installed. My heater motor does not operate.

The switch seems to have one stop when pulled out suggesting single speed heater fan, true?

The heater motor has three wires, one of which is ground. What type of motor is this?

How does the knob come off the shaft, or if the knob and shaft are permanently connected, how does the shaft come out?

I've search this forum for heater wiring diagrams but find nothing for this car. What does the heater wiring diagram look like. I've also searched the Van Pelt site and find nothing for the heater.