On the display
The OptiView Control Center shows SYSTEM CYCLING - CONTACTS OPEN as a cycling shutdown message. The manual prints the text in a single form only, so this exact wording and capitalisation is what to expect on the display. It points to an external input — the System Cycling contacts — rather than to a component inside the chiller.
What it means
The external System Cycling contacts have opened. These contacts are wired to terminal TB4-13 on the I/O Board, and their opening is the signal that initiates a cycling shutdown. If the chiller is running at the moment the contacts open, the Pre-rotation Vanes are driven fully closed before the chiller shuts down. The message therefore reports a stop initiated from outside the control center through the cycling contact input, not a condition measured inside the machine.
Why it appears
- The System Cycling contacts connected to I/O Board TB4-13 have opened to initiate a cycling shutdown.
Reset and restart
No manual reset action is described. Restart is automatic: The chiller will automatically restart when the contacts close.
Until the System Cycling contacts at TB4-13 close again, the chiller stays shut down; once they close, the unit comes back on its own.
Questions engineers ask
What does SYSTEM CYCLING - CONTACTS OPEN mean on a YORK YMC2?
It means the external System Cycling contacts wired to I/O Board TB4-13 have opened, and their opening initiates a cycling shutdown of the chiller.
Why does my YMC2 shut down with SYSTEM CYCLING - CONTACTS OPEN?
Because the System Cycling contacts connected to I/O Board TB4-13 opened. If the chiller was running at that moment, the Pre-rotation Vanes were driven fully closed before the shutdown.
How do I clear SYSTEM CYCLING - CONTACTS OPEN on a YMC2?
No manual reset is described — the chiller will automatically restart when the contacts close again.
Do the pre-rotation vanes move during this shutdown?
Yes. If the chiller is running when the contacts open, the Pre-rotation Vanes are driven fully closed prior to the chiller shutting down.
Messages next to this one
Source
Written from the manufacturer's manuals for the YORK YMC2; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YMC2 messages: fault codes · YORK YMC2 documentation · YORK manuals