How do you protect a reefer load in summer heat?
Pre-cool the trailer to the set point before loading, check product pulp temperatures and note warm product on the bill of lading, load for good airflow, run the mode the shipper requires, and keep doors closed and fuel topped off. Download or record the temperature history so you can prove the load was kept in range.
Summer is when reefer loads get tested. High outside temperatures, produce season volume and long waits at hot docks all push the unit and the product to their limits. Most temperature claims trace back to a few avoidable mistakes, and this guide walks through how to prevent them.
Why summer is harder on reefer freight
Heat works against you from every direction:
- Heat soaks into the trailer walls, floor and doors while it sits in the sun.
- Product may load warm, especially fresh produce picked in the field.
- Door openings at hot docks let in a lot of warm air quickly.
- The unit runs harder, burning more fuel and putting more strain on belts, compressors and alternators.
- Delays cost more, because every hour of waiting is an hour of heat load.
Summer is also busy season for produce in many regions, which means more freight and often better rates. See our guide on the freight market calendar for when produce seasons tend to peak.
Before you arrive: pre-cool and pre-trip
- Read the instructions. Confirm set point, mode (continuous or cycle), and whether the reading is in Fahrenheit or Celsius. A wrong unit setting is an expensive mistake.
- Pre-cool the empty trailer to the set point before arrival, unless the shipper says otherwise. Give it enough time; on a hot day this can take a while.
- Check the unit: fuel level, belts, coolant, alarms and any active fault codes.
- Check the trailer: door seals, air chute, floor drains, and that the trailer is clean and odor-free. Food shippers can reject a dirty trailer.
- Check tires while cool. Heat raises tire pressure, so cold checks give the honest reading.
At the shipper: pulp temps and paperwork
The temperature that matters is the product, not the air. Use a calibrated probe thermometer to check pulp temperature on a few pallets from different parts of the load, following the shipper's rules on how and whether you can probe.
If the product is warmer than the required temperature:
- Tell the shipping office before you leave.
- Ask them to cool it further, or to note the actual temperature on the bill of lading.
- Write the temperatures you measured and the time on your copy of the BOL.
- Notify your dispatcher and the broker.
A reefer unit is designed to hold temperature, not to pull heat out of a trailer full of warm product. If warm product is not documented at pickup, the receiver's rejection may become your claim. Our cargo claims guide explains how claims are decided.
Loading for airflow
Cold air has to circulate around the product and back to the unit. Watch for:
- Gap at the front: do not let pallets block the return air bulkhead.
- Gap at the top: leave space between the top of the load and the air chute so air can travel to the rear.
- Gap at the rear: a small space at the doors helps air return along the floor.
- No plastic sheets or loose cardboard over pallets unless the shipper requires them.
- Floor channels clear, so air can move under the load.
If the load is shipper load and count, you may not control the pattern, but you can note poor airflow conditions on the BOL.
Continuous vs cycle mode
| Mode | How it works | Common use |
|---|---|---|
| Continuous | Unit runs all the time with steady airflow | Many fresh produce and sensitive loads |
| Cycle (start/stop) | Unit shuts down when set point is reached and restarts as needed | Many frozen loads; saves fuel |
Run the mode the shipper or broker specifies. If it is not on the paperwork, ask and get the answer in writing. Do not switch modes to save fuel without permission.
Fuel and the unit on hot days
Summer heat makes the reefer burn more fuel. A hypothetical example: if your unit burns about 0.8 gallons per hour in continuous mode on a hot day, a 30-hour trip uses about 24 gallons. At a hypothetical $4.50 per gallon, that is about $108 of reefer fuel for one load. Price it into your rate, and use the truck fuel cost calculator for the tractor side.
Practical tips:
- Fill the reefer tank before every load. Running out of reefer fuel is one of the most common causes of temperature failures.
- In many states, reefer units can run on dyed diesel from a separate tank. It must never go into the truck's fuel tank. Check the rules where you fuel, and keep reefer fuel separate on your IFTA records.
- Park in shade when you can, and keep the unit's condenser clear of dirt and debris so it can shed heat.
On the road and at the receiver
- Check temperatures at every stop, and photograph the unit display with a timestamp if possible.
- Keep doors closed. If an officer or the receiver needs to open the trailer, note the time.
- Move promptly at the receiver. Long waits in heat add risk. Request detention per your rate confirmation.
- Download or save the temperature record after delivery. Many units keep a log; some brokers require the download with your paperwork.
Food safety rules
The FDA's Sanitary Transportation of Human and Animal Food rule sets duties for shippers, carriers and receivers moving food. For carriers this generally means following the shipper's temperature requirements, providing temperature records when asked, keeping equipment clean, and training staff. Check the current requirements with the FDA.
Summer reefer checklist
- Set point, unit of measure and mode confirmed in writing
- Trailer pre-cooled, clean, and seals checked
- Reefer tank full; unit with no active alarms
- Pulp temps checked and any warm product documented
- Airflow gaps at front, top and rear
- Temperature checked and recorded at each stop
- Temperature log saved after delivery
How Texas Solutions can help
Texas Solutions is a dispatch service, not a broker or a motor carrier. Our reefer dispatch team finds and negotiates produce and temperature-controlled loads, confirms set points and instructions with brokers, handles broker packets and paperwork 24/7, and you approve every load. You can also talk to a dispatcher.
Frequently asked questions
Should I pre-cool the trailer for every reefer load?
Usually yes, unless the shipper says otherwise. A pre-cooled trailer removes heat from the walls and floor so the unit can hold the product at temperature from the start. Turn the unit off while the doors are open at the dock if the facility asks.
Can my reefer cool down warm product?
Not reliably. A trailer reefer unit is built to maintain temperature, not to pull heat out of a full load of warm product. If product loads above the required temperature, document it before you leave.
What should I do if the reefer unit fails on the road?
Call your dispatcher and the broker right away, record the time and temperatures, and get to the nearest reefer repair shop. Fast, documented action protects you if a claim follows.
Is continuous mode always safer in summer?
Not always. Continuous mode gives steady airflow, which many fresh loads need, but it burns more fuel. The right mode is the one on the bill of lading or shipper instructions.
