Classic/Antique Car Repair: 78 newport heater, automatic temperature control, air plenum

Question
my rear defog & heater/AC blower motor wont run. The fuse is good. I jumped the motor with a hot lead & it does operate. I've heard there may be some sort of interior resistor, not sure what it would look like & where its located. Please advise. Thanks

Answer
There is a resistor in the circuit, but it only affects the lower speeds. If it won't run on any speed, there is something else wrong.

If your car has automatic temperature control, the master switch is probably bad - it is a vacuum operated switch on the air plenum with two wires going to it, and a vacuum hose.  It is either yellow or green in color - or you may have both. One controls the AC compressor, the other controls the whole HVAC system.  These switches are shaped like mushrooms, about 1 inch in diameter.  If you have these, just jumper across the two terminals - if that brings the system on, you know that either your vacuum hose is not connected to the source, or the switch is bad (or else you have poor intake manifold vacuum).

If your car does not have ATC your problem could also be in the main system control, or the fuse could be making poor contact in the socket -  you'd best get a 12 volt test light from the auto parts place and poke around to find the problem - it shouldn't be hard to track down.

Dick