The Alarm Code 84 on Thermo King equipment is triggered when the engine fails to reach 40 RPM during the startup sequence or briefly exceeds this threshold before dropping back. This code indicates a failed restart attempt, often associated with previous alarms like Code 17.
Alarm 17, initially a preventive alarm, becomes a shutdown alarm after two failed startup attempts. If Code 84 appears alongside Code 17, it likely means the engine could not sustain the minimum required conditions for operation.
How is Alarm 84 Detected?
The controller activates Alarm 84 when the electrical load generated by the alternator or its frequency drops below a predefined threshold for an extended period. Common causes include:
- Low engine speed (less than 40 RPM).
- Issues with the alternator or drive belts.
Steps to Check and Resolve Alarm 84
| Area to Check | Recommended Procedure |
|---|---|
| Engine RPM | Use an independent tachometer to measure engine RPM and compare it with the controller’s readings. |
| Alternator Functionality | Test the alternator with a multimeter to ensure it generates the correct load within expected limits. |
| Belt Tension | Inspect the alternator drive belts. They should be properly tensioned and in good condition. |
| Output Intensity on Screen | If the device uses a current shunt, check the intensity displayed on the controller screen. |
Interaction of Code 84 with the Control Panel
When Alarm 84 is triggered, the system attempts to correct the underlying condition. In some cases, this involves an automatic waiting period to allow the engine to cool before retrying a startup.
- If the restart is successful: both the initial alarm and Code 84 are cleared automatically.
- If the failure persists: after several attempts, the initial alarm code remains active, requiring manual intervention.
Codes Associated with Alarm 84
Code 84 rarely appears alone; it is often accompanied by other codes such as:
- Code 17: Indicates the engine failed to start after receiving a start command. Check the battery, connection cables, and fuel cut-off relay.
- Code 63: Signals extreme overheating or vapor lock in the fuel system. Ensure the system is properly ventilated and inspect filters and fuel lines.
Final Recommendations
- Prioritize identifying and resolving associated alarm codes (e.g., 17 or 63) before addressing Alarm 84.
- Perform regular preventive maintenance on the alternator, belts, and engine to avoid recurring issues.
- If the alarm persists, consult the technical manual or contact an authorized Thermo King service center.
