Heater Motor not Running - Ground Question

[doubleyellow]

Heater Blower Motor not running. Going to start by checking ground. Non A/C

Where exactly is the factory ground for the blower motor? Is it the engine side firewall? The 3 nuts need clean ground (no paint) to the firewall? or is the ground somewhere under the dash?

Thanks

 

[Challenger RTA]

Heater box.look by the heater tube.

After you clean the grounds and you have power,and won't run.The motor tends to stick from sitting.

 

[Beekeeper]

The ground wire goes from the motor to the metal plate on the backside, as shown in the photo So there needs to be a good connection there but after that, you’d need a good connection from the three mounting holes on the firewall to the firewall itself (chassis ground).

If the motor worked outside the car but not in, then you’re right to assume ground. Obviously, the battery gets grounded to the engine in the front but don’t forget the smaller chassis ground at the radiator support.

Another spot to consider is the small rectangular resistor on the box (shown in the photo) where the green wire is. Power gets sent from the fan switch to one of those two legs and resistance on the inside determines current flow which sets fan speed. A break of the coils inside could be the problem.

 

[Cratos]

did you check the resistor in the heater box? it could also be the Couse

 

[Sinitro]

EZ to check the motor operation...
Run some wires(12V+/12V-) directly to the motor bypassing the resistor pad...

Just my $0.02...

 

[doubleyellow]

EZ to check the motor operation...
Run some wires(12V+/12V-) directly to the motor bypassing the resistor pad...

Just my $0.02...

Thanks everybody for all the input. Will be using all the tips this weekend to find the issue