Thursday, July 21, 2011

Setting the Temp

Refrigerated trailer temperature settings are critical to understand in order to ensure the success of any perishable shipment. All refrigerated trailer units have a “Set Point” that sets the temperature inside the trailer, and this number is shown on the reefers Set Point digital display. Drivers have to physically set the temperature of their refrigerated trailer, and must also select the “mode” that the reefer unit will operate in: continuous or cycle-sentry. Understanding the two different reefer trailer temperature setting options (continuous vs. cycle-sentry), along with what needs to be done to ensure that a produce load will maintain temperature while in transit is key.

Now, let’s explore the difference between the two refrigerated trailer temperature mode settings:

Continuous Setting:
This setting MUST be used for ALL produce loads; they need continuous air flow to handle the heat of product respiration. Continuous air flow means that there is a consistent temperature throughout the trailer for the duration of transport. Temperature recorders can indicate if a trailer has been set to continuous or cycle-sentry. Below, an example of a temperature recorder printout that indicates a shipment has run on continuous:

Cycle-Sentry Setting:
This setting should only be used for frozen loads (i.e. loads that are intended to ship cooler than 24F). Frozen loads can handle more significant temperature variances without causing damage to the product. The cycle sentry setting is a START-STOP setting, so air flow for the refrigeration unit is not constant. When the temperature inside the refrigerated trailer drops between 0.5 and 1F below the Set Point, the unit will turn off. The unit then waits until the temperature inside the trailer warms up 5F above the set point temperature, and will then turn itself back on. For this, reason, produce loads should NEVER be run on cycle!!!! Running a produce load on cycle-sentry greatly increases your exposure to claims and additional charges!!!

Temperature recorders can also indicate if a shipment has been run on cycle-sentry. Below is an example of a temperature recorder printout in this setting:

Some other points to remember:
• Make sure to check the fluids in the refrigeration unit to make sure it will operate as designed.
• Keep the refrigerated trailer on its regular maintenance schedule to ensure all settings are accurate and will work as designed. Preventative maintenance is the best kind!!!
• Pre-cool the trailer to ensure all residual heat inside the trailer walls, floor and ceiling is eliminated prior to loading. This is especially important during these summer months!!!

Have anything else to add? Please share!!!

4 Steps to a Successful Shipment. Sensitech Cold Chain Visibility. Powerpoint Presentation. Received on 11/08/2009, Accessed for document on 21/07/2011.


  1. Your excellent guidelines will be of great help to many. Nice post. I enjoyed reading it.

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  2. Thanks for the comment prolix! We are glad you found it useful and will work to bring more posts like this one!

  3. Thanks for this wonderful post.
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  5. The statement that produce loads should never be set to cycle is false. I am the GM of a tomato repacking facility and if I know ahead of time that the load of tomatoes leaving the farm is very light and I need them to have more color when they arrive I will have the carrier set the reefer on cycle in order to get the tomatoes to "pop" so to speak and have more color when they arrive at my dock.

  6. false is a little harsh,there are gray arias and special needs and conditions that arise in any arena,all in all a very good read,thx

  7. What is the max temperature that a reefer trailer can get to and hold? Nick

  8. Thanks for the well written and interesting article!

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