GM-GMC: drivebelt on 1998 gmc truck, gmc truck, aircond

Question
can i put a belt on without using it on my aircond. pump

Answer
I don't think that the routing would work properly.  Even the trucks that were not equipped with a/c had an idler pulley in place.  Check at a parts store, they may sell kits that you can bolt on in place of your a/c compressor.  I assume your compressor is seized or damaged in some way?  Your other option is to get one from a junk yard that will at least spin so you can use an original length belt.
Hope this helps.