I have a 88 chev pu that when you turn on ac or heater belt squeal and belt stops turning any suggestions. thanks mike

sounds like your a/c compressor is junk. Remove the belt and check to see if the a/c compressor spins freely when it's not engaged. If it does, then engage the clutch and see if it still stops dead. Also look for metal shavings around the compressor's pulley, as they are usually a sign of compressor wear.