A/C system over pressurized but has correct amount of Freon.

[BroncoBuster92]

High pressure switch cuts out at 430PSI so if your pressure relief is venting below that it is bad. I don't think the pressure relief valve is supposed to vent until 450-500 psi.

I believe the valve can be screwed out and replaced without replacing the hose set, the problem is I'm not seeing the valve sold by itself anywhere. You may have to get one from a salvage yard.

This might be it.

https://www.oreillyauto.com/detail/c/motorcraft/motorcraft-a-c-compressor-relief-valve/mot0/yf2813/v/a/5265/automotive-suv-2003-ford-explorer

Sounds like that’s it!

 

[TechGuru]

Sounds like that’s it!

Just make sure you get the correct replacement. Verify the opening PSI on it. I'd try to find a 500psi one.