Quote Originally Posted by gearhead3 View Post
ive actually had this happen almost exactly. when i would get to the site the oil pressure, level and reservoir would all be correct. i would reset sentronic and watch unit checking all operations. i found that the problem was only happening after 1:00am which is when the biggest load was coming out of defrost and also midnight crew was stocking. other techs were under the impression that customers employees were shutting off fans at night because the wif was too cold for them. which i have heard of people doing so. anyways i stayed the night because it also was a 2 hour drive. watched system in defrost and made sure no fans were being turned off. unit was a twin evap walk in freezer. ended up seeing that when coming out of defrost expansion valve on one evap coil was sticking wide open and never closing. replaced expansion valve and problem went away. also found that previous company that installed system 1) was welding with no nitrogen through lines and 2) had cut screens out of expansion valves. this was a month long head ache for our company.
Based on the information provided, this sounds like the more likely scenario to me.

The crankcase becoming overfull and the pump locking out on oil sound like 2 separate issues with the first being a result of the second.

Unless you've got a suction accumilator on the rack, I'd be looking at the circuits nearest your pump as the culprit.