On the display
The Status display shows UNIT WARNING: INVALID NUMBER OF COMPRESSORS SELECTED and keeps it on screen indefinitely — the message does not clear by itself. It is one of the unit warnings, and while it is present, start-up of the unit is inhibited.
What it means
The VSD cannot read a valid compressor count from its wiring harness. The “Number of Compressors Select” jumpers installed in the J1 plug tell the control how many compressors are selected; when the VSD has been initialized and finds none of these jumpers, or more than 1 of them, the selection is invalid and the warning is raised. The unit cannot start while the warning is displayed.
Why it appears
- No “Number of Compressors Select” jumpers are installed in the VSD wiring harness (J1 plug).
- More than 1 jumper is installed in the J1 plug wiring harness.
- These jumpers are factory installed in the wire harness plug and should not require changes, so the warning normally means a jumper has been removed or an extra jumper has been installed in the plug.
What to check
- Turn off both the control panel and the VSD control voltage before handling the wiring harness.
- Inspect the J1 plug of the VSD wiring harness and check the “Number of Compressors Select” jumpers installed in it.
- If no jumper is installed, or more than 1 is installed, install the jumper(s) properly in the VSD wiring harness; the manual's jumper installation instructions cover the placement details.
- Restore the control panel and VSD control voltage and confirm that the warning has cleared from the Status display.
Reset and restart
Clearing the warning is done with the power off and the jumpers corrected. The manual's instruction: To clear this warning, both the control panel and VSD control voltage must be turned off and the jumpers properly installed in the VSD wiring harness.
With the jumpers properly installed and both voltages restored, the warning is cleared and the start-up inhibition is removed.
Questions engineers ask
Why does my YORK YCAV show UNIT WARNING: INVALID NUMBER OF COMPRESSORS SELECTED?
After the VSD has been initialized, the control found no “Number of Compressors Select” jumpers, or more than 1 jumper, in the J1 plug of the VSD wiring harness, so the compressor count is invalid.
How do I clear the INVALID NUMBER OF COMPRESSORS SELECTED warning on a YCAV?
Turn off both the control panel and the VSD control voltage, install the jumpers properly in the VSD wiring harness, then restore power. The warning clears once the jumpers are correctly installed.
Can the chiller start while this warning is active?
No. Start-up of the unit is inhibited while the warning is displayed, and the message stays in the Status display indefinitely until it is cleared.
Do the Number of Compressors Select jumpers ever need changing?
No. They are factory installed in the wire harness plug and should not require changes; this warning means a jumper is missing or an extra jumper has been installed.
Messages next to this one
The same message on other models
Source
Written from the manufacturer's manuals for the YORK YCAV; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YCAV messages: fault codes · YORK YCAV documentation · YORK manuals