YORK YMC2 — EVAPORATOR - TRANSDUCER OR LEAVING LIQUID PROBE

The control center displays this message exactly as EVAPORATOR - TRANSDUCER OR LEAVING LIQUID PROBE. Both manuals print this single wording, so there are no display variants. It is one of the safety shutdown messages: when it is triggered, the chiller is shut down. Note that it is a different message from EVAPORATOR - TRANSDUCER OR TEMPERATURE SENSOR, which the same manuals list separately for this model.

The message means the evaporator pressure reading and the Leaving Chilled Liquid temperature reading are no longer in the correct relationship to each other. The control center converts the evaporator pressure to a Saturated Temperature value and compares it with the Leaving Chilled Liquid temperature. When the two readings fall out of the relationship the control expects, it treats one of the measuring devices as probably defective and initiates this safety shutdown.

• The Evaporator pressure Transducer may be defective.
• The Leaving Chilled Liquid temperature Thermistor may be defective.

1. Read the evaporator pressure and the Leaving Chilled Liquid temperature at the control center; the control converts the pressure into a Saturated Temperature value for the comparison.
2. Apply the manual's accuracy statement: with accurate devices, the Evaporator Saturated temperature is no more than 2.5°F (1.4°C) warmer and no more than 25.0°F (13.89°C) colder than the leaving chilled liquid temperature.
3. Check whether the difference is outside the acceptable range; the shutdown is initiated only after the difference has been outside the range continuously for 10 minutes.
4. Treat the Evaporator pressure Transducer and the Leaving Chilled Liquid temperature Thermistor as the devices to suspect — the manual names these two devices and no others for this message.

• Compared values: the Saturated Temperature converted from the evaporator pressure versus the Leaving Chilled Liquid temperature.
• Difference definition: difference = chilled liquid temp - evaporator saturated temp.
• Acceptable range: the difference should not be outside -2.5°F (-1.4°C) to +25.0°F (+13.89°C).
• Accuracy statement: with accurate devices, the Evaporator Saturated temperature is no more than 2.5°F (1.4°C) warmer and no more than 25.0°F (13.89°C) colder than the leaving chilled liquid temperature.
• Shutdown timer: the difference must be outside the acceptable range continuously for 10 minutes before the shutdown is initiated.

This is a safety shutdown, and the manual gives one recovery action: The chiller can be started after the CLEAR FAULT button is pressed. No other reset procedure is described for this message.