Tri-Pack shooting Freon out of compressor

Hello everybody,

Fired up my Tri-pack today for the first time. Im not 100% sure but I am willing to bet today is the first time she has ran in 18 months. I only assume this because that is how long the truck has been sitting. Once she fired up and cleared her throat out she ran pretty good. After maybe 3-4 minutes of running the relief valve on the a/c compressor popped and she started shooting freon out. I shut her down as fast as possible and did not mess with it anymore.

I am gonna take a wild guess and say its either the electric clutch on the compressor not disengaging or its the high pressure cut out switch not working.

I am just wondering if the Tri-Packs are known to have either of these go bad regularly just to give myself a better idea of where to start on it tomorrow. Thanks