Learn the correct way to pre-cool a refrigerated trailer before loading. Covers pre-cool times by commodity, temperature monitoring, pulping procedures, and common mistakes that lead to rejected loads.
return ( What Pre-Cooling Means and Why It Matters Pre-cooling is the process of running your reefer unit to bring the trailer interior down to the required temperature before any product is loaded.
Shippers will check your trailer temperature with a probe or infrared thermometer before allowing loading to begin.
If your trailer is not at the correct set point, you will be turned away and may lose the load entirely.
The purpose of pre-cooling is to remove residual heat from the trailer walls, floor, and ceiling so the product being loaded does not experience a temperature spike.
A reefer unit is designed to maintain temperature, not to cool down warm product.
If you load 44,000 pounds of fresh strawberries into a trailer that is 55 degrees instead of 34 degrees, the unit will struggle for hours and the product may be damaged before it ever reaches temp.
How to Pre-Cool Step by Step Close all doors completely.
Running the reefer with doors open wastes fuel and will never reach target temp.
Set the thermostat to the required temperature.
This is specified on your rate confirmation or Bill of Lading.
Common set points are 34F for fresh produce, 0F for frozen, and 35-38F for dairy.
Start the reefer unit and set it to continuous run mode.
Do not use cycle-sentry or start-stop mode during pre-cool.
Continuous run provides the fastest pull-down.
Allow adequate time for the trailer to reach set point.
The time varies by ambient temperature, trailer condition, and target temp.
Check the reefer unit display and, if available, your in-cab monitoring system.
The trailer should hold at set point for at least 15 minutes before you open the doors.
Back into the dock and open doors only when directed.
Every second the doors are open, warm air enters the trailer and the temperature rises.
Pre-Cool Times by Commodity These are approximate times assuming an ambient temperature of 85-95F and a trailer in good condition with intact door seals and a properly functioning reefer unit.
Frozen freight (0F or below): 90 to 120 minutes.
Frozen loads require the longest pre-cool because the unit must pull the trailer from ambient all the way to zero or below.
Fresh produce (32-34F): 45 to 75 minutes.
Many require the trailer to hold at 34F for 15-30 minutes before loading begins.
Dairy and beverages (35-38F): 40 to 60 minutes.
Floral and pharmaceuticals (36-46F): 30 to 60 minutes.
These loads often have narrow temperature windows, so accuracy matters more than speed.
Meat and poultry (28-32F): 60 to 90 minutes.
Meat shippers often require proof of continuous temperature monitoring during transit.
In the Southeast summer heat, add 20-30 minutes to these estimates.
An ambient temperature of 100F in Alabama, Georgia, or Florida puts extra strain on the reefer unit and slows pull-down significantly.
Pulp Temperature vs Air Temperature Understanding the di.
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