A/C and blowing fuses

[Brownie82C10]

I have a 1982 Chevy C10 pickup with the straight-6 engine and a mostly operational A/C system. The A/C-heater regulator is an aftermarket model, purchased several years ago from LMC Truck. The A/C system worked up until about nine months ago, when it suddenly stopped working. After a brief investigation, I discovered that the 20-amp blade fuse blows whenever the regulator is switched to cooling or defrosting. With a good fuse, the heating and venting operations work fine.

What do I have here — a short or ground problem at the regulator or somewhere under the hood? What's the next step in the problem solving?

Thanks.

 

[Dave M]

Check the clutch on the a/c compressor, unplug the wire at the compressor, then try it again.

 

[Brownie82C10]

OK, I tried the A/C controls with the wire connector unplugged from the compressor. The fuse blew again when I switched the lever from VENT to AIR COND. What's next with the troubleshooting? Thanks.

 

[Dave M]

OK, I tried the A/C controls with the wire connector unplugged from the compressor. The fuse blew again when I switched the lever from VENT to AIR COND. What's next with the troubleshooting? Thanks.

It's hard to diagnose when you can't see what your working with, or not familiar with the actual system you have. Bit of a hit and miss, keep disconnecting the various components and also look for any damaged wiring.

 

[Brownie82C10]

Thanks. I saw another thread that suggested a ground/short wire problem between the A/C controls and the fuse block. I'll focus on that first.