Stock Heating System

[Guest perfectturmoil]

Hey guys..

 

I have a Datsun 280zx. In around a year or so, I will be doing a tuned SBC motor swap. In the meantime, I am fixing the car up so its road worthy. I have a question.. because I have heat problems:

 

1) At first, the blower did not work. It turns out the fan had power, but no ground. I created a chassis ground, and now the fan turns on and off. However, the system does not have variable fan control (the rheostat is varying the resistance properly, however). Is the rheostat on the ground side of the circuit? If so, I will recreate the system on my own.

 

2) It appears that the vacuum lines are not doing their job. The little switch above the drivers right knee DOES have air running through one of the tubes, but the system does not actuate any of the air direction valves. I do not know what is not working with the system.. any one know how to fix it? Anyone know how to do some more troubleshooting for the system to find what is not working? Or is there a common problem that occurs with this system?

 

Thanks a bunch guys!

[RPMS]

Unless I'm mistaken, the fans take constant 12v power, and vary resistance to the ground. It's the same thing with the instrument light dimming system.

 

Please correct me if I'm wrong...

[Guest perfectturmoil]

constant 12v power, and vary resistance to the ground...

 

Yup thats correct. I was just able to find the wiring diagram in my new service manual. So it appears that something on that side of the circuit has a problem. I know the rheostat is doing its thing. There is also an Amplifier wired into the circuit. Does anyone know what this amp does, and where in the car it is?