Reefer Trucking for Beginners - Temperature Setpoint, Pre-Cooling, and Load Rejection Prevention

Refrigerated trucking—often called “reefer trucking”—plays a vital role in the supply chain by transporting perishable products such as food, pharmaceuticals, and flowers. New drivers may assume that hauling a refrigerated trailer is similar to dry van work, but there are critical differences. Success in reefer trucking hinges on understanding temperature control, pre‑cooling procedures, facility expectations, documentation, and the actions that prevent load rejections. This article provides a comprehensive guide for beginners who want fewer claim issues and smoother receiver handoffs.

How Reefer Units Work and Operating Modes

A refrigerated trailer is essentially a large, insulated box equipped with a diesel‑powered refrigeration unit. The unit circulates refrigerant through a compressor, condenser, and evaporator to remove heat from the trailer and maintain a consistent temperature. Drivers interact with this system via a control panel where they set the desired temperature (setpoint) and select the operating mode.

There are two main operating modes:

• Continuous mode: The reefer runs constantly to maintain the set temperature, cycling refrigerant and air continuously. This mode is recommended for sensitive freight that requires minimal temperature fluctuations, such as fresh produce, dairy products, and pharmaceuticals. Using continuous mode also avoids frequent starts and stops, which can cause greater temperature swings.
• Start/stop (intermittent) mode: The unit runs until it reaches the set temperature, then shuts off until the interior warms to a certain point. This mode is commonly used for frozen goods, where minor temperature fluctuations are acceptable. While start/stop mode saves fuel, it’s not suitable for temperature‑sensitive loads because the temperature rises during off cycles.

Understanding which mode to use is crucial. Shippers typically specify the desired mode on the bill of lading. Selecting the wrong mode can lead to claims or load rejection.

Pre‑Cooling the Trailer

The pre‑cooling process involves bringing the trailer to the required temperature before loading. It prevents product temperature shock and condensation, both of which can damage cargo:

• Clean the trailer: Sweep the trailer floor and walls to remove debris. Inspect for odors or residue from previous loads, especially if hauling food.
• Check fuel level: The reefer should have at least three‑quarters of a tank of fuel before departure. Running out of fuel mid‑trip can shut down the reefer and spoil the load.
• Set the temperature and mode: Using the reefer’s control panel, input the setpoint specified by the shipper. For perishable goods, continuous mode is often required.
• Allow sufficient pre‑cool time: Refrigerated trailers take time to reach the desired temperature. Plan to arrive at the shipper with enough time for the trailer to pre‑cool.

Shippers and receivers may refuse to load or unload if the trailer is not at the correct temperature. Arriving pre‑cooled demonstrates professionalism and protects the cargo from thermal shock.

Managing Temperature Setpoints

The setpoint is the target temperature you program into the reefer unit. Maintaining the correct setpoint throughout the trip is essential to preventing spoilage and claims:

• Follow shipper instructions: Always use the temperature specified on the bill of lading or load confirmation. Do not adjust the temperature without permission.
• Monitor continuously: Modern reefers have digital readouts that display the current box temperature and setpoint. Check the readout periodically during transit.
• Understand temperature tolerance: Some loads require the temperature to stay within a narrow range (±1 °F), while others allow more variation. Continuous mode provides tighter control than start/stop mode.
• Avoid door openings: Each time you open the trailer doors, warm air enters and cold air escapes. Plan loading and unloading to minimize door openings and keep the interior at the setpoint.

If you encounter temperature deviations, document them and notify your dispatcher or the shipper. Being transparent can help protect you if the receiver claims the load was mishandled.

Facility Expectations and Reefer Protocols

Facilities that load or receive refrigerated freight have specific expectations. Meeting these expectations builds trust and minimizes delays:

• Arrive on time: Reefer loads often have tight windows because the product is perishable. Arriving late can disrupt the receiver’s schedule and increase spoilage risk.
• Be pre‑cooled: As discussed, many facilities will not load a trailer until it reaches the proper temperature. Double‑check your setpoint and mode before arriving.
• Wear PPE and follow sanitary rules: Food facilities may require hairnets, gloves, or sanitized shoes to prevent contamination. Always have PPE available and comply with posted guidelines.
• Communicate with facility staff: Let the loader know your reefer is ready and clarify whether they prefer continuous or start/stop mode. Some shippers prefer continuous mode while loading to ensure consistent temperature.

Understanding facility expectations and adhering to protocols reduces friction and speeds up loading.

Documentation and Protecting Yourself

Documentation is your best defense against claims of mishandled freight. Collect and maintain records throughout the trip:

• Temperature readings: Record the setpoint, box temperature, and time at each stop. Some reefers generate printed logs that you can provide to the receiver.
• Fuel receipts: Keep receipts for reefer fuel purchases. Receipts prove that the unit had adequate fuel during the trip.
• Pre‑trip inspection records: Document pre‑cooling steps and any issues discovered during the pre‑trip inspection.
• Bills of lading: Note any instructions regarding temperature, loading procedures, or special handling.
• Communication logs: Record any discussions with dispatch or the shipper about temperature adjustments, reefer alarms, or problems.

When delivering, obtain the receiver’s signature on the bills of lading, acknowledging that the product was delivered at the correct temperature. This documentation protects you if the load is later rejected.

Preventing Load Rejection and Claims

Load rejection happens when the receiver refuses the cargo due to temperature deviations, contamination, or other issues. Preventing rejection involves diligence and proactive problem‑solving:

1. Follow temperature protocols: Use continuous mode for perishable items unless instructed otherwise.
2. Monitor reefer fuel: Fuel gauges can be unreliable; track fuel burn over time and refuel earlier than necessary.
3. Check for reefer alarms: Modern units have alarm codes that indicate problems such as low refrigerant, high temperature, or sensor errors. Familiarize yourself with these codes and contact maintenance if they appear.
4. Document everything: In case of a temperature excursion, your notes and data logger printouts show that you took appropriate steps.
5. Communicate proactively: If the reefer shows an alarm or temperature drift, notify your dispatcher and the shipper immediately. They may instruct you to adjust the setpoint or take the load to a repair shop.
6. Maintain cleanliness: Keep the trailer clean and free of debris or odors. Contamination is a common reason for rejection.

By following these steps, you greatly reduce the risk of load rejections and protect your professional reputation.

Handoff and Receiver Expectations

Delivering a reefer load successfully involves clear communication and professionalism at the receiver:

• Provide temperature records: Show the receiver your temperature log. If required, print a digital temperature report from the reefer unit.
• Wait for inspection: Receivers often inspect the load before signing. Be patient and let them verify product condition.
• Report issues immediately: If the receiver notes damage or temperature problems, document their findings and contact your dispatcher before leaving.
• Obtain signatures: Ensure the receiver signs the bill of lading to confirm delivery and note any exceptions. Keep your copy for records.

Building trust with receivers by being organized and transparent makes future deliveries smoother.

Train the Rules Before the Road

Reefer trucking requires understanding complex systems and strict procedures for temperature control and documentation. The stakes are high—improper handling can cost thousands in spoiled goods. ELDT Nation’s online ELDT theory training demystifies reefer operations through easy‑to‑follow videos and quizzes.