I have a 1994 Chevy truck and I need to recharge the air conditioning. When i hook up the can of R134a Freon the compressor does not engage to suck in the freon. Could it be a bad Air Conditioning Pressure Cycling Switch?
The situation you are running into is normal. The compressor will not engage until there is enough pressure seen at the air conditioning low pressure cycling switch. So what you will need to do is manually bypass the switch with a jumper wire. This will engage the compressor and allow it to suck in the freon. After you have installed one can (14 oz.), then remove the jumper wire and finish the recharge cycle with the pressure cycling switch plugged in.