Thermo King TriPac Evolution APU Error Codes
Tripac APU code 254. Check Inlet Water Temperature Sensor (WT2)
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Tripac APU code 254. Check Inlet Water Temperature Sensor (WT2)

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Replace the sensor in the line (outside of APU) not in the water pump  

Diagnostic Procedure

1. A High temperature reading indicates a shorted sensor or harness.

2. A Low temperature reading indicates an open or high resistance in sensor or harness.

3. Check resistance of the WT2 curciut between WT2 (J6 pin A1) and WT2_RTN (J6 pin B1).

Component Location and Description

This sensor is located on the pre-cooler coil of standard units or an adapter tube in the coolant inlet hose with Arctic option (if installed). This sensor provides information to control the pre-cooler fan and arctic option.

How alarm is set

If the sensor reading is outside of the allowable limit of -58F to 300F (-50C to 149C) and does not return within 10 seconds then Alarm code 254 is set a check alarm. Disable pre-cooler fan and Arctic option while alarm is active. Engine operations will continue as required.

How alarm is cleared

The alarm will automatically clear if the sensor reading returns to the normal range. The alarm can be manually cleared from the HMI Control Panel by turning the system off and then back on.  

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