heater woes Options

[cause]

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. :/

[Superhawk996]

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.