02 Return Air Sensor Open Circuit (Check Alarm)

Thermo King Alarm Code

Description	Corrective Action
Return Air Sensor Open Circuit (Check Alarm) Sensor circuit resistance higher than 100,000 ohms. Temperature below -70C (-94F). Indicates: Open circuit to sensor Defective or wrong sensor Defective relay board Defective cable No.1 Defective controller	Check sensor resistance between pins 3 and 4 on plug j15. Resistance must be 2,000 ohms at 25C (77F)  Check cable No.1 between controller and relay board.