My AC started shutting off after only 2-3 minutes of cooling this morning. What could cause this?

Needs to be checked out by a pro,, could be 1 of several things causing, maybe a shorted wire,bad contactor,bad tstat,

Sounds like it might be frozen up..

FROZEN UP? He didn`t make any comments about seeing ice,, and isn`t likely the motor and compressor would seize up at the same time

You need to check to see where you have power and where you don't starting with the tstat. It will take some time and a voltmeter.