If you jumper the relay, the compressor should just run. Check your horn fuse.

 

Problem is I don't ave a fuse diagram, but I did check all of the fuses, they appear to be ok.

Jump the relay? Sounds scary which pins would I try?

 

Grab the appropriate year service manual for your truck from here. Wiring diagrams, and fuse box layouts are in there.

 

OK. Checked the 20A horn fuse under the hood - it WAS blown!

Put in a new one - horn now works. Turned on the AC - blew the fuse again. How is that possible?

 

You have a short somewhere in the a/c circuit. Gonna have to check the wires, starting from the compressor, and working your way back to the PDC.

 

Thanks! And I appreciate the manual You posted - I can now do the things

 

I would be real careful just jumping the relay...... you apparently have a dead short somewhere..... given the distance from the PDC, to the compressor, it shouldn't be hard to find.

 

I don't think anyone has asked you...did you replace the battery and alternator BEFORE or AFTER the ac comp and radio stopped working? We are trying to help you here bud. I am thankful for the good info I was given from this forum.

 

Yeh - I'm very hesitant do jump it. The problem with the compressor wires is they immediately enter the thick wire bundle. The whole things is very nicely and tightly wrapped. So well in fact, that I'd rather buy a new relay before tearing apart the whole wiring harness...

After. I'm fuzzy about the order of things but I'm fairly certain I got this issue when the battery first went dead.

 

The inter-relationships between electrical devices on these trucks is sometimes quite mysterious...... Solve one problem at a time. Sometimes, fixing one problem, solves a whole bunch of others as well.

Got a volt/ohm meter? Could pull the relay, disconnect the a/c compressor, and then test the wire, see if it goes directly to ground.