A/C Works Intermittently 2000 Chevy Blazer

Disconnect your high pressure switch when the compressor is not engaging and stick a paper clip in the wiring harness.. thus jumping both sides of the wires.. If the compressor engages then you know its a faulty pressure swicth.

You can buy the a/c pressure switch and replace it your self. It's located on the accumulator (air dryer) un-clip the wire harness and remove the switch and be ready with the new switch to replace, it's like replacing a oil sensor. Your not going to loose that much R134a, just have the new switch ready to place in the accumulator. Once placed if you have the gauges for the a/c, the low side should be 30psi to 50psi and the high side should be 150psi to 200psi with the a/c on the highest level. Any other readings will give you poor a/c performance. Good luck and keep me posted.