YORK YCAV — UNIT WARNING: INVALID SERIAL NUMBER ENTER UNIT SERIAL NUMBER

The panel prints UNIT WARNING: INVALID SERIAL NUMBER ENTER UNIT SERIAL NUMBER. This is the only form the manuals give for this unit warning. While the message is on the display it can be bypassed for viewing: press the STATUS key repeatedly to scroll through as many as three STATUS messages that could possibly be displayed at any time. Bypassing only lets you read the other messages — it does not deal with the warning itself.

According to the manual, the appearance of this message may mean the chiller has lost important factory programmed information: the unit serial number is not programmed into the panel. While the warning is present, an Optimized IPLV chiller will only run in Standard IPLV control mode, and Optimized IPLV cannot be enabled unless the serial number is programmed into the unit.

• The serial number is not programmed into the panel.
• The Chiller Control Board was replaced or the EPROM was changed, so the factory programmed information was lost.
• The chiller was not programmed from the factory.

1. Contact YORK Product Technical Support immediately — the manual calls for this as soon as the message appears, and the password needed for the entry is provided by them.
2. Set the date and time on the chiller before programming: changing the programming of this feature requires the date and time to be set first, and the password is time sensitive.
3. Press the SERVICE Key. The panel shows SERVICE MODE XXXXX PRESS ENTER KEY TO CONTINUE.
4. Key in the 5 digit alphanumeric password provided by Product Technical Support and press the √ (ENTER) key.
5. On the S/N ENTRY UNIT SERIAL NUMBER POS 1 screen, key in the first letter (A through Z) of the serial number using the ◄ and ► (ARROW) keys and press the √ (ENTER) key.
6. Press the ▼ (DOWN ARROW) key to scroll to position 2, key in the second letter (A through N) of the serial number and press the √ (ENTER) key.
7. Scroll to position 3, key in the third letter (A through Z) of the serial number and press the √ (ENTER) key. As the serial number is input, the characters keyed in appear in the display, indicating the panel has recognized the entry.

The manual's remedy is to program the serial number into the panel, not to clear the message from the keypad: contact YORK Product Technical Support, then enter the serial number using the Service Key with the factory-provided password, following the steps above. The manual's SERIAL NUMBER PROGRAMMING information carries the complete procedure. Optimized IPLV cannot be enabled until the serial number is programmed, and once the serial-number password has been entered, a second password is needed to activate the optimized IPLV control. Until then, an Optimized IPLV chiller keeps running only in Standard IPLV control mode.