AC Pressure relief valve

[deebee]

My AC pressure relief valve dumped all my charge last night and will not reseat itself (leaks). Called all parts stores and Ford delears for new one. Part is discontinued. No junk yards in area have one. Does anybody know where I can order one or is there a replacement valve? HELP! It was 102 today with a heat index of 110.

 

[MAKG]

Umm, WHY did your pressure relief valve dump? Have you ruled out a blockage?

 

[deebee]

I had the compressor, condensor and dryer replaced within the last two months. During the replacement it was converted to R134. Haven't ruled out a blockage, but the system was flushed during the repairs. Took it to a shop and they tested it and said that the relief was leaking by.

 

[LordVngr]

You might check with these guy's, Auto Air Innovations. I'm taking my 89 2.9L STX to them tommorow for a complete custom R134 A/C build. The owner told me they do a lot of work on older / classic cars and custom work.

LMC truck parts is also a good source for Ranger parts but I didnt see a relief valve in their catalog. Isnt the release valve in the compressor?



LV

 

[MAKG]

LMC truck parts is also a good source for Ranger parts but I didnt see a relief valve in their catalog. Isnt the release valve in the compressor?

Often. But it can be anywhere in the high side, and sometimes it's in the compressor discharge line.

One would think this would be under warranty, given the recent work.

 

[Bob Ayers]

Umm, WHY did your pressure relief valve dump? Have you ruled out a blockage?

A blockage will cause the suction side to go into a vacuum, so a blockage usually will not cause a pressure relief valve dump. With the recent repairs, the system was probably overcharged, or something happened to the airflow across the condensor, causing the head pressure to go to high.

 

[deebee]

Could changing to R134a cause the relief to dump? Not sure what the pressure difference is between R12 and R134a.

Also, since this truck was built as laws changed preventing Freon from being dumped to atmosphere, does anyone know if there is a retrofit kit available to replace the relief with a High Pressure Cut-out switch?

 

[MAKG]

Changing to R-134a correctly will not overpressurize. Given that venting is illegal, it would be a good bet that conversions would be illegal as well were this the case.

But obviously, there are a whole lot of ways to f*** it up.