YORK YVAA — SYS X CONTROL VOLTAGE

The panel prints the message as SYS X CONTROL VOLTAGE for the affected system. In the manual's fault tables the same entry appears as SYS X YYYYYYYY CONTROL VOLTAGE: X is the number of the system involved, and YYYYYYYY reads FAULT or LOCKOUT. The manuals list this message under the system safeties (faults).

This safety alerts the operator that the 115 V AC control voltage to one of the systems is missing; the manual calls it the System Control Voltage Cutout. The affected system faults and shuts down immediately when the 115 V AC supply is lost. The safety is deliberately scoped to a single system: it will not shut down a system if the UNIT switch is OFF, because that switch electrically removes the 115 V AC to all systems. It is only used to indicate a situation where a single system is missing the 115 V AC.

• The 115 V AC supply has been lost to a single system.
• The loss may be due to a system fuse that has been removed or is blown.

1. Read the system number X in the message — it identifies the system that is missing its 115 V AC control voltage.
2. Check the 115 V AC supply to that one system.
3. Check the system fuse serving that system; the manual names a fuse that has been removed or blown as the possible reason the supply is gone.
4. Confirm the loss affects a single system rather than the whole unit: with the UNIT switch OFF the 115 V AC is electrically removed from all systems, and this safety does not shut a system down in that case.

This safety does not cause a LOCKOUT. The manual's stated action is: Will not cause a lockout; the system fault resets when power is returned. Restoring the 115 V AC supply to the affected system returns power to it, the system fault resets, and the message clears. No other reset procedure is described for this safety.