Ok, so I ran over a curb at low speed and busted a left side radiator.  Replaced the radiator.  No apparent damage to the AC condenser and the AC works.  Last PM I notice a grindy/growly/rattle sound coming from what sounded like beneath the passenger seat (too soon to be coincidental.)  when I turned off the AC, immediately stopped.  Would the compressor rattle if the refrigerant was getting low or just stop running at low pressure.  Aux fan maybe?
Things to check?