The Alarm Code 35 on Thermo King equipment, designed for refrigeration and transport, indicates a critical issue requiring immediate action. This alarm, marked by a red warning, is triggered when the main relay fails to activate properly. This malfunction is often linked to irregularities in the charging and starting circuit, detected during the system’s self-check performed by the controller.
Common Causes of Alarm 35
1. Battery Issues
- Defective or damaged cells:
A faulty battery can disrupt the electrical system and trigger the alarm. Use a digital multimeter to test the battery’s condition and address any detected issues, such as damaged cells.
Importance: A poorly charged or malfunctioning battery can significantly impact system performance.
2. Fuse Failures
- Inspecting the main fuses:
Check the fuses protecting the Thermo King system circuits. A visual inspection can reveal blown fuses or defective connections.
Associated relays: Also check the system’s relays, replacing or repairing damaged components to restore proper electrical flow.
3. Alternator Problems
- Faulty operation or defective connections:
The alternator should be tested to ensure it properly charges the battery. A correctly functioning alternator will increase the battery’s voltage while the equipment is running.
Testing with a multimeter: Set it to DC voltage mode to confirm a voltage increase during operation.Recommended steps:- Excitation terminal (B): Check the voltage output to rule out issues with the regulator or alternator itself.
- Voltage sensor connections: Inspect the cables and their condition.
- Belt condition: Ensure it is in good shape, properly tensioned, and check for unusual noises from the alternator.
4. Electrical Cables and Connections
- Ground connections: Verify they are secure and in good condition.
- Cables: Identify and repair any damaged, cut, or corroded cables that may disrupt current flow.
5. Software Issues
- Software updates: Some models may experience software malfunctions, particularly with codes 28 and 35, due to incompatibilities or errors during pre-trip tests.
Context: During testing, Thermo King alternators consume less amperage than Bosch alternators, potentially causing incorrect error recordings and triggering alarms.
Recommended Solutions
- Battery: Test and replace if necessary to ensure proper charging.
- Fuses and Relays: Inspect, replace, or repair damaged components.
- Alternator: Verify its operation, connections, and belt condition.
- Cables and Connections: Ensure all cables and ground connections are in excellent condition.
- Software: Update the software to avoid conflicts that may generate errors.
