I have a York YK chiller, full model # is YKDPDSQ3-CKG. The problem I am currently experiencing is that the unit is generating a fault of High Oil Temp.

This fault is created when the oil temp reaches over 180. There is a brazed plate heat exchanger that controls the oil temp, fed liquid refrigerant directly from the condenser, through an expansion valve, and then into the evaporator through a ball valve. I watched it run for around 3 hours one day and I could see the oil temp climb slowly.

not much to the oil cooler, so I figured it had to be the expansion valve ( all of the refrigerant valves ARE open). I replaced the valve and monitored it for 2-3 hours. everything seemed okay.

Unit tripped the next day again.

Any ideas?