Need some help on SC heat circuit

[jcunning]

Now that it is getting colder out, I'm trying to get the engine blower working.
For background, I have a 1982 SC chassis with a 3.2 engine.

I have narrowed down the problem to not getting power to the yel/blk wire to the blower motor.

I definitely have power at the heater blower relay on pins 30 and 86, but the relay is not switching on when I pull up on the levers.

I'm stuck trying to understand what the yellow wire actually does when you pull up on the heater levers.

Does it provide the ground when the levers are up or when they are down?
It seems like I get a closed circuit only when the levers are down.

I find it strange as the diagram indicates the yellow wire is a +50 wire, which means it only gets power when the key is in the start position. I have confirmed this with a voltmeter.

All help is appreciated!

[jcunning]

For those interested, I did some additional work and did manage to get the blower working. I found that the contact switch on the heat levers wasn't working as I first thought. Once I adjusted the contacts, I found that the yellow wire is a ground wire for the relay.

I guess the wire loses ground when you start the car to make sure the blower turns off while trying to start the car.

The wiring diagram isn't very clear about this behavior, but that is how it works.

[tonythetarga]

Glad you found your problem. If you search around you will find that there are a handful of guys that have some excellent info to share with respect to the heating system in these cars. One in particular is a user named 'mysterytrain'. Search his name and you might also find other helpful tips. Also a lot of guys with SC's install the footwell blower system from the Carrera for extra heat.
good luck.