Thermo King’s Alarm 03 code indicates that the unit is not receiving a valid signal from the return air sensor for the specified zone. This could be attributed to various factors, including a faulty or damaged return air sensor, a loose or disconnected connection to the return air sensor, or issues with the unit’s wiring.
Causes of Thermo King Alarm 03:
- Faulty or Damaged Return Air Sensor: The primary component monitoring the return air temperature may experience damage or defects. Alarm 03 is triggered when this sensor fails to send a valid signal.
- Loose or Disconnected Connection to the Sensor: A simple connection issue could be the underlying cause. Checking the connections to the return air sensor is crucial to ensure uninterrupted data flow.
- Problems with Unit Wiring: If the wiring connecting the sensor to the unit is damaged or poorly connected, it can result in a loss of signal, triggering Alarm 03.
- Defective Regulator: The regulator, responsible for maintaining the proper functioning of the sensor, may experience faults affecting data transmission.
Information from Thermo King Alarm 03: Alarm 03 is presented with a yellow light and suggests the following actions:
- Check (control) the return air temperature sensor (zone): Manually verify the return air temperature to ensure the sensor is functioning correctly.
- Manually check the temperature: Confirm the temperature manually to corroborate the sensor’s information.
- Report the alarm at the end of the day: Record and report the alarm at the end of the day for proper follow-up.
Thermo King Alarm 03 Diagnosis
- Open Circuit:
- When the Thermoking system uses a PT1000-type sensor, the system module detects an open circuit if the resistance measurement of the sensor circuit is greater than 1300 Ω.
- Short Circuit:
- Short circuit detection occurs when the resistance of the sensor circuit is less than 602 Ω.
Location of the Issue Generating Alarm 03:
- Faulty or Incorrect Sensor: Identifying whether the sensor is damaged or improperly installed is essential to resolving Alarm 03.
- Defective Wiring: Check the wiring for short circuits or loose connections that may affect data transmission.
- Defective Regulator: Verify the regulator’s status to ensure it is functioning correctly and not impacting the sensor’s performance.