Allright,, Fred is an idiot, don't take his advise. The resistor is burning out because the electrical ingagement clutch in the compressor is bad. The comreossors are a dime a dozen in a junk yard,, get one were the resistor is still in tact, adn swap it over as a unit. ie, the compressor must be repalced.

its a resistor. It needs to be there so as not to overload your compressor. Its getting too much voltage somewhere. have you checked your wires with a voltmeter? might look for a haynes or chiltons and see if you can find some wiring diagrams for it and re-trace everything. Its been so long since I've messed with one I cant remember what all you need to check off the top of my head. try a search for chevytruck forums and ask in there, you'll probably get a better answer from somebody there. I always left the A/C off my older hot rods and cruisers. Id be more worried about burning out wiring in the vehicle than the compressor being hurt. Not sure if you were talking about a truck or car but the ideas the same and a truck forum is probably going to be easier to find and have plenty of people active to help out.