I have been chasing an issue for about a year with the air conditioning on my wifes 08 trailblazer it has the 4.2 engine. The air just quit working one day so i replaced the pump and checked all fuses and replaced the relay. Still didnt work. I tested the power to the pump no power. Tested the prongs on the relay thats good. But the relay wont trigger to let the clutch kick in unless i ground my test light and touch the relay trigger prong.


Do i just need to trace down ground wires or is it something else.

 

Welcome from Florida. Did you check the low pressure switch? Try jumping it and see if that helps.

 

i did try that nothing happened. It only kicks on if i ground the trigger prong on the relay with my test light. The light is very dim when i do this.

 

is there a low and high pressure switch? I dont usually deal with ac stuff but its the wifes vehicle so she wants it it fixed haha