Protect the cargo and preserve the temperature history
A warm reading can come from excessive heat load, poor airflow, an operating input or an equipment fault. Replacing a component before recording the circumstances can hide the cause. Preserve alarms and the time-stamped temperature history while following the cargo’s approved excursion procedure.
Keep the cargo decision separate from the vehicle repair. The cargo owner or approved quality procedure determines whether the product remains acceptable. The service technician needs the unit identity and operating conditions to assess the equipment.
Separate safe observations from service work
Record loading temperature, door events, visible airflow obstruction, frost or drainage conditions, and power or fuel status only where the manual allows safe operator observation. A warm reading alone cannot diagnose a refrigerant fault, and neither bypassing controls nor chipping ice is an appropriate shortcut.
Scroll horizontally to view all columns.
| Decision | What to establish | Condition or limit |
|---|---|---|
| Cargo and doors | Record starting product temperature and infiltration events. | The unit may be functioning but overloaded by the duty. |
| Airflow | Check safe visible supply and return blockage. | Do not enter unsafe moving or energized equipment areas. |
| Frost and drainage | Record frost pattern, defrost status and visible drainage. | Do not chip ice from components or bypass controls. |
| Unit fault | Preserve alarms and operating data for qualified service. | Refrigerant, electrical and fuel-system work requires qualified personnel. |
Keep the temperature record with its operating conditions
A technician needs the unit identity and operating conditions to interpret a temperature record. Thermo King publishes selection guidance for named units; neither a unit name nor one empty-box reading establishes performance on a loaded route. Thermo King truck quick reference guide
Preserve the raw time-stamped readings and exceptions against the agreed cargo acceptance band. Record ambient temperature and the initial cargo and box temperatures. Describe the load arrangement and door-opening schedule, with the insulation and door condition. Include sensor locations and calibration, the power mode and the recording interval. These are the conditions to agree for a test, not evidence that a KEEYAK test has been completed.
Scroll horizontally to view all columns.
| Condition | Record | Interpretation |
|---|---|---|
| Pull-down | Initial box temperature, ambient, power mode and empty or loaded state | Do not equate empty-box cooling with cooling warm cargo. |
| Delivery operation | Cargo, airflow paths, door events and route duration | Review all probes and excursions against agreed criteria. |
| Model identity | Unit, body, insulation and software or control settings | A result for another model or body is contextual evidence only. |
Send the fault history with the route conditions
Include the body and unit identities, sensor locations, alarms and recent operating events. Refrigerant, pressure, fuel and electrical work belongs to qualified service personnel. Keep the findings and return-to-service decision with the original record rather than replacing it with a single reading after a reset.
Information to send with the service request
- Setpoint and independent temperature record
- Cargo type and loading temperature
- Ambient, route and door-opening history
- Airflow and loading layout photographs
- Alarm codes, power and fuel status
- Unit model, serial and maintenance history
Records to request and keep
- Time-stamped box and cargo temperature record
- Ambient, route, loading and door history
- Alarm, mode, power and unit identity record
- Service diagnosis, repair and return-to-service evidence
Common mistakes and what to check instead
- Turning the setpoint lower without recording the fault: Preserve data and follow the approved response plan.
- Assuming every warm reading means low refrigerant: Check duty, doors, airflow, frost and controls before qualified diagnosis.
- Accepting cargo based on air temperature alone: Use the cargo-owner quality and excursion procedure.
Service and safety limits
This guide is not a refrigeration repair or food-safety decision procedure.
Qualified service personnel must handle refrigerant, electrical, pressure and fuel systems.
Stop service and protect cargo for smoke, electrical hazards, fuel or refrigerant concerns, uncontrolled temperature or failed door security.
Sources and applicability
Manufacturer selection reference for the listed Thermo King units and stated body and operating assumptions; not proof for another unit.
Sources checked:
Controls the project-input, quotation, approval and inspection workflow described in this guide.
Provides public checklists and worksheets; the signed project documents remain controlling.
Defines the relevant product family and published configuration boundaries. Project-specific ratings require the selected OEM documents.
Primary public guidance supporting preconditioning, airflow, door-seal and loading checks. Cargo-owner and destination requirements remain controlling.