Has anybody ever had the pop valve blow on their a/c compressor while trying to charge the system

 

I never knew there was such a thing.

 

I didn't either.....the fsm shows one on the high pressure line....but this little booger is right on top of the compressor in front of the high side. Was charging the system after vacuum yesterday and the vent thermometer would make it down to 60 degrees and the relief valve would blow. then the temp would go back to 72 out of the vent. Makes me wonder if i have a blockage in the system, or would the expansion valve cause this?

 

According to the FSM, the high pressure relief valve is on the discharge mufler and activates at 450-550 psig and reseals itself when pressure returns to normal. It also says that pressures rise when air flow is restricted, have you checked your evaporator to see if it is blocked up? It also indicates air in the system, but since you pumped it down and it held vacuum, this is not likely. If your problem is in the compressor, it coud be bad, is it aftermarket?...Mark

 

I know nothing about the compressor....was already on truck when i bought it. Do you mean internally blocked on the epaporator...or the fins pugged up. the fins are clean.

 

There is a pretty good diagnostic flow chart in the FSM. I was talking about the fins. Sounds like maybe a bad compressor, but I would try some of the diagnostics first. I do know that the best time to charge an ac system is on a hot, dry day. The system is most efficient on those days. I assume that you had gauges on the unit when it vented, did you notice the high side pressure when it happened? ...Mark

 

we had the low side hooked up, but the hose for the high side wouldn't fit. The fitting on the high side of the truck was to small, so i got an R 134 adapter to put on the line today and try the gauges tomorrow.

 

There is a similar thread going on right now and it makes me wonder if maybe the original compressor is not compatible with 134-A. I know newer ones are and I have no personal knowledge the originals aren't, maybe somebody smarter than me will chime in...Mark

 

Mine blew on me a few times before I figured out that the fins in the condenser were no longer attached to the tubes.

JP.

 

make sure you are getting sufficient airflow across the condensor to take the heat out of the freon. or check for a restriction in the h valve.

 

Thanks guys....gonna tackle it this weekend

 

Hounddog, i'm having same problem,,,,,,don't know how to retrive my 134 that i just putin( anyone can jump in and tell me how), . Guess i will pull it all apart again. Do the dryers on our trks., have screens or filter in them???? Keep us posted & if you get it figured out ,,,,,let us know.Good luck.

 

They do not, most GM systems do...Mark

 

thanks mark, can we install bigger dryers??? If this seems like a dumb question just over look some of us.

 

Like all my teachers always told me, there are no dumb question, which meant to me that all of mine were dumb . I don't know if you can, but it shouldn't be necessary. There is a really good trouble shooting guide in the FSM. I am coming home tomorrow and I can scan it in for you. Should be home by mid-afternoon, if the narcotraficantes don't kill me ...Mark