1984, 944 heater motor circuit
 

The motor works when motor shorted to the battery to check it, and the control works to activate it. No fuse or relay is listed. Where is the fuse and the relay?

fuse #10 in the main box 16Amp
you problem is most likely the fan resistor, they have a tendency to corrode and lose connection and/or cause extreme resistance in wire. it is located right under the cowl, under the hood.

Cowling, you say
 

I know the term cowling, but don't know how to reference it to a resistor location. I see a resistor under the small motor cover which controls the motor speeds, but don't believe that is the one you are directing me toward. How about a little more info on location, firewall v. fenders v. readiator?