Heater Help!

[carter_gordon]

I am trying to get the heater working on my 81 SC. The way I understand it when you pull the handles next to the emergency brake it starts the blower motor, but my blower motor is not getting power. There are no blown fuses, and I am getting power to the micro-switches by the brake (I read 12 volts when the switch is open and 0 volts when closed), where do I go from here?

Thanks as always guys!

Bud Gordon

[john walker's workshop]

the contacts under the heat levers ground the relay on the rear electrical panel. (to the left of the engine). the relay is the common round, black one like those above the front fuse panel. the relay should have battery power at all times, key on power also, the relay receives a ground when the lever is lifted, and then the blower gets power. it already is grounded. so check power at the blower plug, and work back from there.

[carter_gordon]

Thanks! I'm working on it now.

Bud

[carter_gordon]

Dumb question buy why 2 micro-switches? Is does not look like a two speed blower.

Thanks again

Bud

[Doug Zielke]

One switch for each lever.

[carter_gordon]

Thanks, I understand that there are 2 micro-switches (one for each lever) what I ment to say was why are there 2 levers?

Thanks

Bud Gordon

[wckrause]

You have separate control of left and right side heat/defrost. The blower comes on when either one is lifted.

[carter_gordon]

Thanks for the help guys. I think that I have a bad relay. When I lift the left heat control lever I get 12V between pin 30 and pin 85. I loose the ground (pin 85) with the lever down. I am going to list the pins below to help the next guy working on his heater. Can someone tell me what pin 87A does?

Thanks again

Bud

Wehrle
21131-12 Volt
911.615.109.01

Pin 30 Constant 12V+
Pin 85 -12V when the key is on and the cabin lever is up
Pin 86 +12V when key is on
Pin 87 +12V to blower motor
Pin 87A Unknown

[Hladun]

A good way to fix problems with the round relays is to take a pocket knife and spread the pins by inserting the blade into the X slots on each pin. Be careful not to break the pins. This expands the pins and makes for better electrical contact.

[john walker's workshop]

take that relay and swap it for the horn relay on the front board. if the horn still works, then it's something else. or put the horn relay back there and see if the fan works.

[Superman]

The blower is a low-impact part of the heating system. Without it, you'll still have plenty of heat as long as the rest of the system is working well. The valves under the car are the real key to heat. That and hoses that are not leaking.