YORK YK — Oil - Low supply temperature

The panel shows Oil - Low supply temperature; some printings of the manual give it in capitals as OIL - LOW SUPPLY TEMPERATURE. Both spellings are the same event. The manuals list it among the safety fault messages of the oil cooling control, and its clearing is described as a manual clear, so it does not reset by itself.

The message means the oil supply temperature has fallen too far below its setpoint. With oil cooling control enabled, and after the chiller has been running for 5 min (the other manual for this model gives 30 minutes), the oil supply temperature, as sensed by the oil supply temperature thermistor, has decreased 15°F below the oil supply temperature setpoint and has stayed there for 1 min — the second manual words it as lower than the oil supply temperature setpoint − 15.0°F for 1 continuous minute. The control then trips this safety fault.

• Oil cooling control is enabled — the fault is defined only for this state.
• The run-time condition is met: one manual sets it at 5 min of running, the other at 30 minutes.
• The oil supply temperature, sensed by the oil supply temperature thermistor, drops 15°F (printed as −15.0°F in the second manual) below the oil supply temperature setpoint and holds there for 1 min.

These trip conditions are the only causes the manuals give; no component failures or external causes are listed for this message.

1. Check that oil cooling control is enabled — the fault only occurs in this state.
2. Read the oil supply temperature from the oil supply temperature thermistor and compare it with the oil supply temperature setpoint; the trip point is 15°F below the setpoint.
3. Note the running time at which the message appeared: one manual allows the trip after 5 min of running, the other after 30 minutes.

• Oil supply temperature setpoint — the reference value the trip is measured against; the passages print no numeric value for it.
• Trip margin: 15°F below the setpoint, printed as −15.0°F in the second manual.
• Trip duration: 1 min below the margin, continuously.
• Run time before the trip logic applies: 5 min in one manual, 30 minutes in the other.

This is a manual-clear fault. The fault is released when the oil supply temperature has risen back above the trip threshold — the second manual gives the release level as the oil supply temperature higher than the oil supply temperature − 15.0°F — or when the chiller is in a stopped state, and the clear control for the listed event is then pressed. The chiller can be started after the temperature rises above the trip threshold or the chiller is in a stopped state, and the Clear button is pressed next to the listed event on the Systems Details Screen. The other manual names this control the Clear Fault key and also calls the action a manual clear.