Reefer trucking basics for owner-operators

How a reefer unit works

A reefer is a refrigerated trailer. The unit on the front wall usually has its own diesel engine. It blows conditioned air through the trailer and can cool or heat to hold the setpoint, the temperature the shipper wants.

• Continuous mode: the unit runs all the time, so air keeps moving through the load. Shippers often ask for it on fresh produce and other freight that needs steady airflow.
• Start-stop or cycle mode: the unit shuts off once the box reaches the setpoint and restarts when it drifts. It saves fuel, but airflow stops between cycles.

Use the mode and setpoint on the bill of lading (BOL) or the shipper's written instructions. If the paperwork says continuous, don't switch to cycle to save fuel. If the instructions are missing or don't match the BOL, call the broker or shipper before you leave the dock.

Pre-cooling, the BOL and pulp temperatures

• Pre-cool: under the FDA rule, the shipper specifies the operating temperature in writing, including pre-cooling if needed. A carrier must pre-cool each refrigerated compartment as the shipper specifies before offering the trailer for food that needs temperature control for safety. Arrive with the box at temperature, not still pulling down.
• Read the BOL: check the setpoint, Fahrenheit or Celsius, the mode, and any notes. Make sure the unit display matches before you sign.
• Pulp temperature: this is the temperature inside the product itself, checked with a probe thermometer. A reefer is made to hold temperature, not to cool warm product. If the product is warmer than the setpoint, call the broker and write the readings on the BOL before you sign. Some shippers won't let you probe. Then ask them to note their own reading on the BOL.
• Photos: take time-stamped photos of the unit display, the seal and the load before the doors close.

Loading for airflow

In most reefer trailers, the unit pushes cold air along the ceiling toward the doors. The air moves down through and around the load and comes back to the unit along the floor. Anything that blocks that path creates warm spots.

• Don't block the unit's return air at the front wall.
• Leave space between the top of the load and the ceiling so air can travel to the back.
• Use the trailer's floor channels and pallets so air can return under the load.
• Keep the doors closed as much as you can at the dock and in transit.

The shipper usually loads the trailer. If the load blocks airflow, tell the shipper and the broker, and note it on the BOL.

FDA sanitary transportation rule: carrier duties

The FDA's Sanitary Transportation of Human and Animal Food rule (21 CFR Part 1, Subpart O) covers shippers, loaders, receivers and carriers that move food by truck or rail in the U.S. When a carrier agrees with the shipper in writing to be responsible for sanitary conditions, the carrier must:

• Make sure the trailer and equipment meet the shipper's specs and keep the food safe.
• Pre-cool refrigerated compartments as the shipper specifies.
• If the receiver asks, give the operating temperature the shipper specified. If the shipper or receiver asks, show that the temperature was kept during the trip, for example with a unit download or temperature log.
• Give information about previous cargo and the last cleaning when the shipper asks.
• Have written procedures for cleaning, temperature control and keeping food separate from non-food items.
• Train personnel in sanitary transportation and keep training records. The FDA offers a free one-hour online training module with a printable certificate.

Records: keep written procedures for 12 months after you stop using them, and training records for 12 months after the person stops doing that work.

Not covered: businesses with less than $500,000 in average annual revenue, and food fully enclosed in a container unless it needs temperature control for safety, among other exemptions.

Reefer fuel and taxes

The reefer unit burns fuel even when the truck is parked, so count it in your trip costs. The trip fuel cost calculator has a reefer option.

On federal fuel tax, IRS Publication 510 says off-highway business use includes fuel used in a separate motor that runs special equipment, such as a refrigeration unit. A credit or refund is allowed for the federal tax on undyed diesel used for a nontaxable use. If the reefer draws from the same tank as the truck, you must figure how much the reefer used. The IRS allows a reasonable estimate based on your experience and backed by your records. Keep reefer fuel receipts and hour readings separate, and ask your tax preparer before you claim anything. State fuel tax rules are separate, so check with your state.

Seasons and where produce ships from

Reefer demand moves with harvests. USDA's Agricultural Marketing Service tracks refrigerated truck shipments of fruits and vegetables:

• In the second quarter of 2024, U.S. truck shipments of fresh produce were 11.21 million tons, up 14% from the first quarter.
• Shipments from Mexico were 3.52 million tons that quarter, more than from any other reported origin.
• California shipped 3.29 million tons, or 29% of the total.

USDA also publishes the weekly Specialty Crops Truck Rate Report and truck availability data by shipping area. Check them to see which areas are busy before you reposition. Our reefer dispatch team watches these seasons for you.

Detention and claims

• Detention: reefer loads often wait at cold storage and grocery warehouses, and the unit keeps burning fuel. Get free time and the hourly rate on the rate con. See how to get detention paid.
• Liability: under federal law (the Carmack Amendment), a carrier is liable for actual loss or injury to the freight it hauls. A carrier can't give less than 9 months to file a claim or less than 2 years to sue.
• Claims process: FMCSA rules say a carrier must acknowledge a written claim within 30 days and pay, decline or make a firm offer within 120 days.
• Your defense: the BOL with the setpoint, your pulp readings, photos, the seal number and the unit's temperature download. A rejected load is much easier to fight with these.
• Insurance: ask your agent about reefer breakdown coverage. Some cargo policies exclude it. See trucking insurance explained.

Questions carriers ask