Finally assembled all of the missing bits to put heat in my car—however I am now running into electrical issues it seems.

what I think are two separate issues I'm experiencing:

1. When testing to see if the fan works at all, I had it disconnected from the main wiring harness and used a jumper wire to connect it directly to the battery—which it does come on, but doesn't need to be grounded with the second wire, is that normal?
2. (Without the fan plugged into the harness still) Only when I have the relay in the circuit board and when heater lever is engaged it sparks and the wire gets super hot/melty. I understand that its just a ground wire, so where could the voltage be coming from and shorting out?

If any folks are decently local to NY/NJ area I'd really appreciate extra eyes on figuring this out—im so close yet so far. :/

Which wire is getting hot? The one in the cab?
What sparks? The lever or the relay?

I'm way up by Ithaca so I wouldn't be much use.

Your heater wiring is jacked up and shorting. As you stated, the motor is supposed to be controlled via switched ground.

Schematic and DMM will be necessary to troubleshoot and repair.

I don’t guess at electrical issues.

First step is measure with DMM and confirm that you do indeed have 12v on the heater control wire instead of Ground.

Well, idk what I did—but I took everything apart and put it back together again (for the 15th time) and now everything works...

I wrote a very long and focused recovery note on resurrection of these motors.

http://www.914world.com/bbs2/index.php?sho...=367558&hl=

They are very interesting self-centering electric motors..........What is sometimes lost is the insulation that is between the mounting bracket and the motor. It isolates the vibration and ground from the connection between the motor and the chassis of the car.

My guess is that you are missing this insulation and the motor is always grounded.

Great thread and in my car two things had happened. The car had sat and the PO discarded the fan which had frozen. I purchased a working one too replace it but upon inspection found that plugging in the lead would short and blow the fuse. Turns out, the brown wire to the handle had melted the insulation to the feed circuit in the tunnel . I surmised that the previous owner let the car sit which froze the motor which heated up the grounding wire screwing up the harness leads. Replacing the wire and a second hand fan that functioned remedied the problem.

I can only say it took a few days of head scratching to figure out what was wrong.