thanks for reading this. I am working on a 91 chevy silverado. I have a friend that has been doing auto ac for 20 + years- but we are stuck on this one? we replaced the ac compressor, accumulator,orfise,ext. ext. we also converted to 34 . every thing has been gone through. we vacuumed the system. THE PROBLEM= AS WE WERE ADDING THE 34- IT WAS STARTING TO COOL ON MEDIUM HIGH- AS WE PUSHED THE BUTTON TO HIGH COOL. THE AC SWITCH IN THE DASH STARTED TO FLASH. THEN ALL POWER TO THE AC WAS LOST. WE DISCONNECTED THE BATTERY TO RESET THE SYSTEM AND IT WORKED FOR ABOUT A MINUTE. THEN IT WENT OUT COMPLETELY INCLUDING POWER TO THE AC SYSTEM IT SELF [COMPRESSOR+FAN BLOWER] NOTHING WORKS NOW. YES WE DID CHANGE THE SWITCH CLUSTER ASSEMBLY IN THE DASH!! STILL NO POWER. AND WE CHECKED THE FUSES IN THE FUSE BOX ONLY. PLEASE HELP!

 

Check for excessive pressure (high pressure side) in the system that could have triggered a cutout switch.

 

we fixed it! I think? 1 the wires to the accumulator were not making contact, but my friend said that has nothing to do with the ac cluster switch? they only control the ac clutch [on and off] ? but I wiggled the wires under the dash next to the blower assembly+blower relay. every thing came back on! yes its cold..