The Thermo King Alarm 02 is a critical signal that indicates the unit is not receiving a valid signal from the evaporator coil sensor for the specified zone. This issue can result from various factors, including a faulty or damaged evaporator coil sensor, loose or disconnected connections, or problems with the unit’s wiring.
Causes of Thermo King Alarm 02:
- Faulty or Damaged Evaporator Coil Sensor: The primary component responsible for monitoring the evaporator coil temperature may be defective or damaged, triggering Alarm 02 when it fails to transmit a valid signal.
- Loose or Disconnected Connection to the Sensor: A potential cause lies in the connections to the evaporator coil sensor. If these connections are loose or disconnected, it can lead to the loss of a valid signal.
- Problems with Unit Wiring: Issues in the unit’s wiring, connecting the sensor to the control system, can disrupt the signal transmission and activate Alarm 02.
Description of Thermo King Alarm 02: Alarm 02 is indicated by a yellow light and recommends the following actions:
- Check the evaporator temperature sensor (zone): Manually verify the temperature to ensure the sensor is providing accurate information.
- Manually check the temperature: Confirm the temperature manually for further validation.
- Report the alarm at the end of the day: Document and report the alarm’s occurrence at the end of the day for proper follow-up and resolution.
- Open Circuit:
- Detected when using a PT1000-type sensor, the system module identifies an open circuit if the resistance measurement of the sensor circuit exceeds 1300 Ω.
- Short Circuit:
- Short circuit detection occurs when the resistance of the evaporator coil sensor circuit is below 602 Ω.
Location of the Issue Generating Alarm 02: In a video prepared by conforempresarial, a detailed description of Thermo King Alarm 02 is provided, along with recommendations for addressing the problem. Key verifications include:
- Faulty or Incorrect Sensor: Check for damaged sensor cables and verify sensor connections to the controller.
- Defective Wiring: Examine the unit’s wiring for potential faults that may disrupt signal transmission.
- Voltage Supply Issues due to Defective Regulator: Consider problems related to voltage supply, potentially caused by a defective regulator.
What to Do with Alarm 02?
Temperature Sensor:
- Inspect sensor cables for damage.
- Verify sensor connections to the controller.
- For Pt1000 sensors, check if they are two-terminal sensors that can be swapped without affecting measurements.
- Disconnect the sensor and use a multimeter in the Ω position to measure electrical resistance between the two sensor cables.
- Understand that a Pt1000 sensor has a positive temperature coefficient, meaning resistance increases with temperature.
- Utilize the provided table for normal resistance values at various temperatures.
Conclusion: Effectively addressing Thermo King Alarm 02 requires a systematic approach, considering potential issues with the evaporator coil sensor, wiring, and voltage supply. By following the recommended troubleshooting steps, operators can identify and resolve the root cause, ensuring the unit operates smoothly and preventing disruptions in temperature control.