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Reefer Downloads: Why they don’t tell the whole story

Trading Assistance

Somewhere right now a produce buyer and seller are discussing the streams of temperature and mechanical data from a reefer download. They’re perhaps scratching their heads and maybe arguing a bit. And then, at some point, the truck broker and the carrier join the discussion, or fray, as the case may be.

Somebody points to the set point. Somebody else points to the supply air temperatures. Another advocates for the importance of the return air temperatures, while another tends to agree with whatever its customer says.    

Given the multiple streams of data provided by reefer downloads (temperature and mechanical data from a carrier’s refrigeration unit), it’s not always clear where to start when reviewing a download. 

What’s more, even if the parties can eventually reach a consensus regarding the reefer download, additional questions arise: how should the readings from the portable recorder be factored in?

After all, prior to the advent of temperature logging capabilities on reefer units, portable recorders were the sole direct source of information air temperatures in the trailer (pulp temperatures being an indirect source). 

And how much leeway do carriers get? Surely temperature control doesn’t need to be perfect, but how much imperfect is okay?

In this article, we’ll explain how Blue Book’s Trading Assistance team approaches these questions.

Location, Location, Location

At the outset, it’s important to recognize that despite all data provided, the temperatures recorded by the reefer download do not tell the whole story because these readings are taken from the nose of the trailer on the reefer-side of the return-air bulkhead wall.  

Even the most carrier-friendly advocates (i.e., carriers themselves), recognize the need to protect the full load of perishable cargo placed in their possession by maintaining temperature control throughout the trailer.   

A carrier that only maintains air temperatures in the nose of the trailer, while failing to cool the rear of the trailer, for example, has not done its job.   

This is one reason why portable recorders continue to be placed in trailers (usually in the rear of the trailer) more than a decade after temperature logging capabilities in reefer units became ubiquitous. 

It seems clear enough, that these days, readings from portable recorders and reefer units must both be considered to fully assess transit temperatures. 

Measuring Sticks

Another fundamental difference between reefer downloads and portable recorders is that reefer units can respond to, and to a large extent control, the temperature readings.

So, even if it’s warm outside and the trailer’s insulation is poor, a reefer unit will respond by supplying colder and colder air until the desired return air readings are reached. Consequently, we generally expect to see return air readings that are very close to the set point, usually within one (1) degree Fahrenheit.   

But, of course, readings from portable recorders will rise without triggering any corrective response, resulting in much greater variance than we typically see on a reefer download. For this reason, we apply different measuring sticks to readings from portable recorders versus reefer downloads.

Section (6.2) of our Transportation Guidelines provides the following rule of thumb for readings from portable recorders (this section was derived from administrative rulings issued by the U.S. Department of Agriculture (USDA) assessing “normal transportation conditions” (see 7 CFR 46.43(j)) under the Perishable Agricultural Commodities Act (PACA)—

Slight deviations in transit temperature based on, among other things, the location and accuracy of the temperature recorder, are inevitable and permissible. What constitutes a “slight deviation” will vary, but as a rule of thumb air temperatures within the trailer should not deviate more than four (4) or five (5) degrees Fahrenheit from the instructed transit temperature. If a temperature range is specified, any deviation will be assessed from the midpoint of the specified range. A temperature variance lasting less than twelve (12) hours may also be categorized as a slight deviation, depending on the extent of the variance, the relative perishability of the commodity, and other circumstances; e.g., a shipment involving multiple pick-ups or drops may be expected to experience temperature variance during loading and unloading. Nothing in this section should be interpreted to suggest a temperature deviation was slight, and therefore permissible or excused, when product has been frozen in transit.    In the absence of an agreement to the contrary, refrigeration (or “reefer”) systems should be set to run continuously, and not on a start-stop or cycle basis.  

Carriers are expected to maintain air temperatures throughout the trailer. Accordingly, air temperature readings from a single recorder may show a breach of the contract of carriage even if air temperature readings from other locations in the trailer do not.

Meanwhile, the note to Section (6.3) of our guidelines pertaining to reefer downloads explains—

We typically expect return air readings to be within 1 degree of the set point and the difference between supply and return air readings to be within 4 to 5 degrees. Greater variances for prolonged periods may suggest improper temperature control. For example, when the difference between supply and return air readings exceeds 4 to 5 degrees during the warm afternoon hours, this may suggest the trailer’s insulation was inadequate.  

Now, of course, every dispute needs to be assessed on a case-by-case basis. And additional factors such as pulp temperatures, multiple pick-ups or drops, and missing recorders may come into play. 

But these measuring sticks applied to reefer and portable temperature readings provide a standard parties can use for assessing and resolving disputes informally. 

At the same time, in a more formal setting, such as arbitration, if the temperature readings for a particular shipment are outside these ranges it may very well be difficult for carriers to establish “freedom from negligence” under the common law of common carriage.  


Digital pundit types are fond of saying, “We are awash in information, but short on insights,” or words to that effect. But, at least where reefer shipments are concerned, the data from reefer units and portable recorders can provide both the information and the insights needed to resolve temperature claims.   

This is a Trading Assistance column from the November/December 2023 issue of Produce Blueprints Magazine. 


Doug Nelson is Vice President of Trading Assistance for Blue Book Services