YORK YMC2 — EVAPORATOR - LOW PRESSURE - SMART FREEZE

The panel shows EVAPORATOR - LOW PRESSURE - SMART FREEZE. The manual prints this wording as the only variant, and the message belongs to the YMC2's safety shutdown messages.

Smart Freeze protection timed out with the evaporator below the freeze threshold: the protection is activated and has shut the chiller down because the evaporator temperature has been below the Smart Freeze threshold for greater than the allowable number of seconds. The count behind this trip is incremented once for every second the evaporator refrigerant temperature is below the freeze threshold, and it is never decremented below zero — it can only keep growing while the temperature stays under the threshold.

• The evaporator temperature has been below the Smart Freeze threshold for greater than the allowable number of seconds, so the protection has shut the chiller down.
• The trip can only happen while Smart Freeze is active, which requires the feature to have been enabled by a service technician and the Leaving Chilled Liquid temperature Setpoint to be less than 38.0°F (3.3°C).

• With the Evaporator Refrigerant Temperature sensor RT7 enabled — using the procedure in the YORK YMC2 Service Manual — that parameter is used as the evaporator refrigerant temperature and the freeze threshold is 32.8°F (0.4°C).
• With RT7 not enabled, the evaporator refrigerant temperature used is the Evaporator Saturation Temperature, derived from the Evaporator Pressure Transducer, and the freeze threshold is 34.0°F (1.1°C).
• Smart Freeze is activated only if the feature has been enabled by a service technician and the Leaving Chilled Liquid temperature Setpoint is less than 38.0°F (3.3°C).
• Seconds to freezing = (4053.7) / (freeze threshold - evap. refrigerant temp.); the further the evaporator refrigerant temperature sits below the freeze threshold, the smaller this number of seconds is.