27 Heat Capacity Test Error (Check Alarm)

Thermo King Alarm Code

Description

Corrective Action

Heat Capacity Test Error (Check Alarm) Occurs during Pretrip (PTI) test only. Difference between supply and return air temperature too small with high speed evaporator fans (less than 0.4 C [0.7F]}. Indicates: Incorrect location of supply or return air sensor Air leakage at supply, return or evaporator coil sensor cable Defective supply or return air sensor Interchanged sensor connections Defective heater elements Incorrect evaporator fan rotation or high speed operation Container/side panels, defective, damaged or leaking

Enter Manual Function Test and start evaporator fans on HIGH speed. Then select Sensor Checks test and operates fans 2 to 5 minutes. Check supply, return and evaporator coil (defrost) sensor temperatures. Sensor readings should be the same (evaporator coil may be 0.5 C [1.0 F] lower due to fan motor heat). NOTE: this sensor check does not detect air leakage around the sensor cables Open evaporator door and inspect evaporator fan rotation. make sure fans are rotating correctly on high speed. Check the sensor connections.