HELP!!! AC/Electrical problem

Great Website!!! Schematics are hard to understand though... How do you find all that stuff inside the truck? Is there a certain way to read them???

 

Electrical problems can drive you nutz!

 

I see this is an old thread but I've had the same problem on my '04 379 lately. Just for future reference I went through all the fuses and switches both in the dash and under the hood. Still no sleeper A/C. Finally I thought about the harness and come to find out there's a big wad of plugs located between the sleeper boot and interior to the right of the passenger seat. The wide flat plug had began to disconnect causing intermittent A/C. Pushed it back together and zip tied it. Good to go! Hope maybe that helps someone

 

Thank you so much for this post!!!

This was exactly what was wrong with my sleeper blower not working. The previous owner must have gave up and literally ran a wire directly to the battery box to run the fan.... So wrong way to fix it.

I checked the wires behind the passengers seat that pass from the cab to the sleeper. Sure enough the large RED power wire had literally shorted across to the next wire (which is a speaker wire) and melted the plastic connector. My solution was to cut the RED wire on both sides of each connector and install a bullet connection on the RED wire only. And --- Bamb the fan now works. Removed the crazy wire running to batter box. I can see why this wire did short... For some reason the way the big bundle of wire was installed at the factory coming from the sleeper had to be twisted in order to make up the connector coming from the cab. In doing so it put strain on the RED wire causing it to short to the next wire. Seems like the factory would have caught this and taken care of it....???

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hi i have a 03 peterbilt 379.. the breaker in the fuse panel for the bunk looks like it has been fried. i switched it out .if i turn on the front ac switch i am ok but soon as i turn on the rear bunk switch on the dash it blows the fuse with a giant arc an pop .. it even does it with the compressor unplug. can someone help me..

 

was you blowing fuses an breaker for the bunk control on dash with this issue

 

That wouldn't cause a fuse to blow. Your problem is a short in the electrical system.