York Logic Board 331-02507-601/031-02507-000

York VSD Logic Board (331-02507-601/031-02507-000/031-02649-001/031-01620-000) - Common Faults and Troubleshooting

Compiled from the fault list in the official York YCIV Series manual, the following are the six most frequently triggered alarms for this board:

① Power Supply (Hardware) Fault - "VSD LOGIC BOARD POWER SUPPLY"

Several DC power supplies on the logic board are monitored by on-board hardware. If any of them falls outside its allowable limit, the unit shuts down immediately. This is an auto-restart safety: it restarts once the fault clears, but locks out on the third fault within 90 minutes, after which the operator must clear the fault manually from the keypad.

Action:​ Measure the individual DC output voltages on the board. If they remain abnormal after the external supply and fuses have been ruled out, replace the board.

② VSD Logic Board Failure (Software) Fault - "VSD LOGIC BOARD FAILURE"

After the Chiller Control Board issues a voltage and frequency command, the PWM generator must acknowledge and handshake back. If the system microprocessor does not receive the handshake within 1.5 seconds, the unit trips. This safety is only active during precharge and while a compressor is running.

Action:​ Power-cycle and reset. If the fault recurs repeatedly, the logic board is most likely defective.

③ Run Relay (Software) Fault - "VSD RUN RELAY"

Two types of run command - a hardware run signal and a software run signal - must both be asserted within a 5-second​ window. If either signal is missing, the system faults.

Action:​ Check the run-signal wiring from the Chiller Control Board to the VSD Logic Board and the relay output.

④ VSD CT Plug (Hardware) Fault - "VSD CT PLUG"

Jumpers are installed in each current transformer (CT) plug on the logic board to feed back a signal indicating whether the plug is seated. If a plug is not installed, the unit shuts down immediately.

Action:​ Reseat the CT plugs firmly.

⑤ Loss of Communications - "VSD LOSS OF COMMS"

The Chiller Control Board and the VSD Logic Board communicate over a three-wire, opto-coupled RS-485 data link at 9600 baud. If communications are lost for 8 seconds, the chiller faults.

Action:​ Inspect the communications cable, termination resistors and grounding. Note that at power-up, if the Chiller Control Board does not receive the initialization data (number of compressors and VSD software version) within 8 seconds, it will keep requesting the data and also report this fault.

⑥ High VSD Ambient Temperature Fault - "HIGH VSD AMBIENT TEMP"

A National LM34 sensor​ on the board monitors the VSD internal ambient temperature. If the temperature exceeds the software trip point, the unit shuts down on this safety.