On the display
The display reads UNIT WARNING: !! LOW BATTERY !! CHECK SETPOINTS/PROGRAM/OPTIONS/TIME. The message is classified as a unit warning and is displayed indefinitely. Unit warnings are not logged to the history buffer; this message is displayed when the STATUS key is pressed.
What it means
Every time the micropanel is powered up it checks the Real Time Clock (RTC) battery. At this power-up the battery voltage was determined to be low, so the clock battery is weak or bad. Because the battery could no longer hold them, all programmed setpoints, program values, time, schedule, and history buffers have been lost and were reset to their default values — values that may not be the appropriate operating values for this unit. The unit is prevented from running until the MANUAL OVERRIDE key is pressed.
Why it appears
- The RTC (Real Time Clock) battery voltage was determined to be low when the micropanel checked the battery at power-up — the manual lists a low or bad battery as the condition detected when powering up the micropanel.
What to check
- Press the MANUAL OVERRIDE key — the unit is prevented from running until this key is pressed.
- Check the setpoints, program values, time, and schedule: all of them were lost at power-up and reset to default values that may not be the correct operating values for this installation.
- Review any other relevant program parameters. After MANUAL OVERRIDE is pressed, the anti-recycle timers are set to the programmed default anti-recycle time, giving the operator sufficient time to check these values.
- Replace the RTC battery as soon as possible. The manual puts it plainly:
If a low battery is detected, it should be replaced as soon as possible.
Reset and restart
Recovery is by key press rather than a reset routine: the unit is prevented from running until the MANUAL OVERRIDE key is pressed, and once it is pressed the anti-recycle timers are set to the programmed default anti-recycle time so the operator has time to check setpoints, program values, and other parameters. If the low battery is not replaced, the programmed values will all be lost again and the unit will be prevented from running on the next power interruption.
Questions engineers ask
What does UNIT WARNING: !! LOW BATTERY !! mean on a YORK YVAA?
The micropanel checks the RTC (Real Time Clock) battery at every power-up and found its voltage low. All programmed setpoints, program values, time, schedule, and history buffers were lost and reset to default values, which may not be the appropriate operating values.
How do I get the YORK YVAA running again after this warning?
The unit is prevented from running until you press the MANUAL OVERRIDE key. After that, the anti-recycle timers are set to the programmed default anti-recycle time so you have time to check setpoints, program values, and other parameters.
What happens if I do not replace the RTC battery?
All programmed values will be lost and the unit will be prevented from running on the next power interruption, which is why the battery should be replaced as soon as possible.
Is the low battery warning stored in the history buffer?
No. Unit warnings are not logged to the history buffer; the message displays indefinitely and is displayed when the STATUS key is pressed.
Messages next to this one
The same message on other models
Source
Written from the manufacturer's manuals for the YORK YVAA; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YVAA messages: fault codes · YORK YVAA documentation · YORK manuals