hi everyone thanks in advance for your help.i wil start from beginning,this winter i noticed that my heat was coming out the defrost and floor only no matter what position i put the dial and it also would only work on the highest setting and at that it was finiky and sometimes not come on at all.well summer arrives and im a landscaper and want to use my ac and at first i get nothing except when the high speed setting decides to activate mysteriously but never would it start the compressor,so i replaced the relay with new gm relay and i get nothing and then i change both fuses that were good to begin with and still nothing.i then replaced the resistor and control switch to no avail nothing except the mysterios high speed come on here and there but never does it activate the compressor.so i pull the ac relay and jump a wire from side to side pins (closest to exhaust of under hood fuse box) and low and behold the compressor engages and blows ice cold air out the defrost and floor.so then when gooogling i came across a gentelman who said jump the low pressure switch and high pressure switch to see if they are bad,but that didnt work without also jumping the a/c relay at the same time.i put a test light on the wire going to the lower pressure and high pressure switches and i have nothing even with relay jumped...also with clutch engaged pumping out cold air to the cab i checked the pressure and my generic gauuges say i was good.im thinking after what i have read that it could be the a/c heat control panel having a bad circut.any help would be great