Heater Fan

[Mantruck-k5]

I'm trying to get my heater/AC going again in my 77 Blazer. It seems the previous owner liked to rip things apart... As it is, my fan will only blow in the "Max AC" position. I replaced the fan switch and I cleaned the switch with all of the vacuum lines attached to it. Is this a problem in some relay or do I have a leak in the vacuum lines or what? Thanks for any help...

 

[diesel4me]

No "Speeds"?

If it works only on "hi",you might have a bad resistor for the speeds on the blower motor--its located in the heater box near the motor on non A/C trucks,ones with A/C might have it inside the truck,( follow the wire off the motor,it goes between the motor and the wiring)you should be able to see it with the glove box open(pull the liner down and it will "flip" open all the way!)--it has a plug with 3 wires on it,and is held in by two screws--if any of the "spring" looking coils on it are broke,you wont get any current to the blower--hence,no "speeds",only "HI" ,which is direct to the motor....

 

[Mantruck-k5]

Problem

Thanks for the reply. I've been researching this thing and I think I'm missing the whole resistor assymbly alltogether. I have the entire distribution box removed to change the heater core and I can not find a resistor anywhere. I guess I have to go to the wrecking yard to see what it looks like on a 77 model unless someone here can post a picture for me.
Also, does the vacuum switch one the AC control use all of the ports? Only half of mine are utilized. Should the unused ones be capped???