Why did my AC compressor blow out?

[Jprps]

I'll have to plug it back in and check to see of its cycling yet. Not sure how much refrigerant it lost. It seems to me the fan wasn't kicking on at idle at all and it built too much pressure. I thought Id the high pressure sensor failed it would keep the fan running as a fail safe? Can I check the sensor with an ohm meter? The fan not cycling to bring the pressure down is what puzzles me.