heater pull and turn switch

[familyfast64]

Hey guys, real quick, I replaced a leaking blower motor with a new unit that isn't sealed like the old one. anyway when I turn it on by pulling the knob out and turning it one or two clicks nothing happens. Under the dash I noticed there's four terminals or male ends of the switch for wires to plug too but only one wire is hooked up. It's a new wiring harness with the fuse box like newer cars have. The blower motor has the one wire plugged into it. Coolant gets hot in the hoses there even before the thermostat items up but I assume that's normal as heat rises from the block. Could you tell me if I'm missing something? I know its hard, lol but if you could tell me for sure that one wire is not enough running to the switch on the dash then I'll take it from there I guess. Oh and I also tried swinging the handle underneath but nothing seemed to happen. I need to purchase a book on the truck just to learn about the heater.

[ClemsonChevy]

The way the speeds on a heater work for these trucks is this:
There is a set of resistors that knock down the voltage on the way to the blower motor for lower speeds. If you have low, med, high speeds the low speed may step the voltage down to 8 volts or so making the fan turn slower. In the med posistion it may send 10 volts to the fan making it turn a little faster. On high, it doesn't use any resistors and sends full 12-13 volts to the fan making it turn the fastest. Those resistors are wire wound and sit in the ductwork of the heater to have the hot air blowing through the duct cool the resistors. They look like this:



Sounds like yours is only wired for high speed. on our trucks the resistor pack is under the dash, on the side of the ductwork facing the firewall. All of the wiring from the switch would normally go to the resistor pack, then a single wire would come from there to the fan.

[familyfast64]

Thanks bud, I'll have to look for that. Tonight I went into town it was cold and I pulled the knob, and moved the lever underneath and got warm air coming out. There is only one setting for speed tho no matter what position the knob is in. I'll have to check it out but I'm happy that it does blow a lil.

[familyfast64]

Ok so if I add the wiring needed from the resistor to the switch(knob) would you know the order off the resistor they would be to the knob ?. Lol sorry if it's confusing, I'll figure it out. Thanks

[ClemsonChevy]

I'll try to take a look at mine today and see.