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A/C Question


June 25, 2006
Reaction score
City, State
Las Vegas, NV
Year, Model & Trim Level
1994 XLT
It seems a high pressure relief "pop-it" valve actuated from the connector block on the back of the compressor. This is a 1994 Explorer with R-134. Can this valve be reset or will I need to replace the hose?

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If that valve "popped off", the system has a restriction on the high side. That is a safety device, not sure if it resettable, or if it resets on it's own.

It resets on its own BUT once tripped they seem to trip earlier next time.

As already mentioned.. Do you know why it went off? If there is a restriction in the system that will need to be fixed or it will pop right off again.. (think plugged orifice tube)

If it did it once and hasn't done it again (and the a/c is still cold) the system may have been overcharged OR your not getting enough heat out of the condenser. Thats usually dirt/crap in the fins of the condenser AND/OR the fan clutch has gotten weak over time.


A new hose that did not include the high pressure cut out switch was installed. The system was vacuumed down and re-charged just fine, but on the first drive the safety valve popped. I installed the high pressure cut out switch and started to test the system, but the poppet let go again. I discharged the system and removed the poppet. It seems to just be an allen screw drilled completely thru and a spring. I'm not sure if this is adjustable or what. Ignorance really gets in the way sometimes :)

mine done the same thing ... I had heard once they pop you need to replace them ... I did and replaced my orifice tube and that was my problem ... it was stopped completely off !! the orifice was like $2 and the pop off was around $20 ... have to get the pop off at ford as its a dealer only item, but it was in stock when i went to get it

i replaced those and refilled the system with freon and its ice cold now !! don't forget if you open it on your own to get away as soon as it starts spitting freon as breathing it can kill you !!

I decided, since it has to be evacuated to replace the poppet valve, I'm changing the accumulator, the other hose and installing a new variable orifice tube.

So I bought the high-pressure relief valve, a variable orifice tube, an accumulator and the condensor to evaporator hose all for $100. Installed today. Pulled a vacuum and charged the system. At 108 degrees ambient air temp I set the idle to 1800 rpm and I have 40psi on the low side, 335psi on the high side and 60 degrees coming out of the center vent. I am calling this a win. Thank all.