YORK YMC2 — EVAPORATOR - TRANSDUCER OR TEMPERATURE SENSOR

The control center shows EVAPORATOR - TRANSDUCER OR TEMPERATURE SENSOR and the chiller has tripped on a safety shutdown. The manual lists this message among its safety shutdown messages and prints it in only this one form.

The evaporator pressure and refrigerant temperature readings are inconsistent, which the control center treats as a probable sensor defect. It converts the evaporator pressure into a saturated temperature value and compares that value with the optional Evaporator Refrigerant Temperature Sensor (RT7). When the two temperatures stay apart by more than 3.0°F continuously for 1 minute, the control center concludes that either the evaporator pressure transducer or the refrigerant temperature sensor is likely defective and performs this shutdown.

• A possible defective Evaporator pressure Transducer.
• A possible defective Refrigerant Temperature Sensor (the optional Evaporator Refrigerant Temperature Sensor, RT7).

1. Confirm the chiller has been running for at least 10 minutes — the control center performs this check only then.
2. Confirm the Evaporator Refrigerant Temperature Sensor (RT7) is enabled; only a Service technician can enable it, following the YORK YMC2 Service Manual.
3. Confirm the chiller is NOT in Brine cooling mode — the check is not performed in that mode.
4. Confirm Smart Freeze is enabled — the check runs only when it is.
5. Confirm the readings sit where the check applies: the Evaporator Temperature Sensor (RT7) or the Evaporator Saturation Temperature is indicating less than 32.0°F (0°C).
6. Compare the Evaporator Saturation Temperature derived from pressure with the RT7 reading; a difference greater than 3.0°F held for 1 minute is what produced this shutdown.

• Trip threshold: difference between the evaporator Saturated Temperature (converted from pressure) and the RT7 reading greater than 3.0°F. The two manuals print the metric equivalent differently: 1.7°C in one, 5.4°C in the other.
• Trip duration: the difference must persist continuously for 1 minute.
• Restart threshold: the two temperatures within 3.0°F of one another (printed as 1.7°C in one manual, 1.77°C in the other).
• Check preconditions: at least 10 minutes of running, RT7 enabled by a Service technician, NOT in Brine cooling mode, Smart Freeze enabled, and RT7 or Evaporator Saturation Temperature below 32.0°F (0°C).

The shutdown does not clear by itself. The chiller can be restarted once the readings agree again: the chiller can be started after the temperatures are within 3.0°F (1.7°C) of one another and the CLEAR FAULT button is pressed. The second manual prints the restart difference as 1.77°C instead of 1.7°C.