98 GMC,, we put new compressor,, dryer,, office tube ,blew everything out,, and the compressor will not cycle on,, we change the low pressor switch,, on the dryer,,i think that what it is called. with one that we know works from another truck and still won't cycle on. we also put a jumper wire in and compressor comes on and air gets cold and works great,,But when ya plug the switch back in on dryer,,it won't kick compressor on. like i said we replaced the switch on dryer with one we know works and it still will not come on,, any ideas would be a big help,,thanks Rhonda