On the display
The shutdown is logged as MON XX:XX AM - PROX SENSOR SAFETY SHUTDOWN. This is the only wording the manual gives for this message — the panel prints exactly this text, with the day and time the control center puts at the head of each shutdown entry.
What it means
This is a safety shutdown: the axial position of the compressor high speed thrust collar is out of range. The Proximity/Temperature Sensor measures the distance between the compressor high speed thrust collar and the sensor probe against the stored Reference Position. When that distance moves outside the allowed band, the chiller is shut down and locked out.
Why it appears
- The distance between the compressor high speed thrust collar and the sensor probe increased by 10 mils or more from the Reference Position.
- The distance decreased by 20 mils or more from the Reference Position (25 mils with EPROM version C.02F(T).12 or later).
What to check
- Do not attempt to restart the chiller — the message is a lockout, and the chiller cannot be restarted until the steps below are complete.
- Have a qualified service technician perform a visual inspection of the high speed thrust bearing.
- Only after that inspection may the technician perform the special reset procedure, which is detailed in YORK Service manual, Form 160.49-M2.
Setpoints and thresholds
- With EPROM version C.02F(T).11: if the reference position is below 42 mils, the minimum allowed distance is 22 mils.
- With EPROM version C.02F(T).12 or later: if the reference position is below 44 mils, the minimum allowed distance is 19 mils.
Reset and restart
This message is a LOCKOUT. The manual states it directly: If the chiller has shut down displaying this message, it cannot be restarted until a qualified service technician performs a visual inspection of the high speed thrust bearing and performs a special reset procedure.
The special reset procedure is not printed with this message; it is detailed in YORK Service manual, Form 160.49-M2. The manual adds: Failure to perform the visual inspection prior to restarting the chiller could result in severe compressor damage.
Questions engineers ask
What does PROX SENSOR SAFETY SHUTDOWN mean on a YORK YK?
It is a safety shutdown for an out-of-range axial position of the compressor high speed thrust collar: the proximity sensor measured a distance to its probe at least 10 mils larger, or 20 mils smaller (25 mils on EPROM version C.02F(T).12 or later), than the Reference Position.
Can I clear PROX SENSOR SAFETY SHUTDOWN and restart the chiller myself?
No. The message is a lockout: the chiller cannot be restarted until a qualified service technician visually inspects the high speed thrust bearing and then performs the special reset procedure from YORK Service manual, Form 160.49-M2.
What are the minimum allowed distances behind this trip?
With EPROM version C.02F(T).11, a reference position below 42 mils sets a 22-mil minimum allowed distance; with C.02F(T).12 or later, a reference position below 44 mils sets a 19-mil minimum allowed distance.
What happens if the chiller is restarted without the thrust bearing inspection?
The manual warns that failure to perform the visual inspection prior to restarting the chiller could result in severe compressor damage.
Messages next to this one
Source
Written from the manufacturer's manuals for the YORK YK; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YK messages: fault codes · YORK YK documentation · YORK manuals