To have heat, would be nice.......

[thedudeabides86]

Good evening, gearheads!

I’ve got a ‘72 C20 with no heat. It does not have factory air. I’ve had this truck for 25 years and never has the heat worked. Where would you start to figure out the problem? I just replaced the slide switch assembly and when I had it started a couple days ago I played with the switches and had no fan or air pushed out so the blower motor might be bad? Or maybe fuses? I’m still learning the way to fix things on this that I’ve never had to fix before. Any suggestions would be appreciated. Thanks everybody!!