2016 Peterbilt 587 Electrical problems

[Alexp86]

Still trying to figure out the issue I'm having. I've spent a long time looking through wire cleaning grounds etc...

The biggest issue for me atm is the a/c defroster not working. When I click the snow flake to turn the cold air on or if I put it on defrost its popping the fuse.

I've unplugged the compressor and it still pops when I click that snowflake, so I unplugged the high and low pressure switch and it didint pop. If I plug 1 in it doesnt pop but with both switches plugged in it pops.
Does anyone know what could be causing this? I had a friend tell me it's the computer that will need to be replaced and I'll be looking at 5000+ is this true?