Skip to main content

Sensitech Q&A to Improve Cold Chain: Question One

Thermometer next to open tractor trailer loaded with pallets

Sensitech® is well known in the industry for its TempTale®GEO monitoring devices. We have a team of experts in various disciplines including refrigeration, food science, life science, logistics and process improvement, who provide services and support to our customers to help them continually improve their cold chains. Throughout the years, the Sensitech Food Global Professional Services and Project teams have received numerous questions from our customers regarding how to determine the root causes of temperature issues.

This blog is the first in a series addressing some of these frequently asked questions.


What steps should be taken when a TempTale recorder indicates temperature problems have occurred?


Contrary to popular belief, temperature problems in a refrigerated trailer are not often caused by malfunctioning equipment. Rather, temperature problems are almost always the result of a process issue. The following five steps highlight a common process to follow when attempting to identify the root cause of a temperature problem. Use these steps and ask yourself these questions:

STEP ONE: Document how the refrigeration unit was programmed

  • What temperature set point was used?
  • Is there evidence suggesting the temperature set point or the reefer mode was changed, or that the unit was shut off during transit?
  • What refrigeration mode was used - Continuous or Fuel Saver mode? Continuous mode keeps the refrigeration compressor running and makes minute adjustments that result in very consistent temperatures. Fresh perishables should utilize continuous mode. Fuel Saver mode allows the temperature to fluctuate.
  • What defrost setting was used?

Carrier refrigeration unit control module

Reefer Time & Temperature Charts - Continuous vs Cycle

STEP TWO: Obtain documentation of the loading temperature

If possible, obtain shipper records for product temperature at the time of loading.

If the shipper cannot provide loading temperature records, it is an indication that care may not have been taken to ensure loading occurred at the proper temperature. When the center of the pallet is warm and the outside is colder, this is often an indication that the product was loaded warm.

Temperature probe and ideal locations to measure temperature of products on pallets

STEP THREE: Document how the product was loaded on the trailer

Proper loading is important to ensure good airflow throughout the trailer.

  • Is the load stacked above the red line?
  • If the trailer has no red line, is the top of the load impeding airflow or constricting the air chute?
  • Are the pallets touching the walls and doors of the trailer? For shipments in Europe, this is common as the dimensions of the trailers and pallets leave little free space. Ideally, there should be at least a small gap between the pallets and the wall to allow airflow and avoid conduction of heat through the wall and into the product.
  • What defrost setting was used?

Top view of properly loaded pallets inside trailer

Photos of correct and incorrect pallet locations inside trailer

STEP FOUR: Document the condition of the trailer

  • Is the air chute damaged? A damaged air chute can cause the airflow to short circuit; most of the air supply gets diverted to the refrigeration-unit end of the trailer, and does not reach the door end of the trailer. The resulting poor air flow often results in high temperature recordings at the door end, often showing a day/night cycle, with good temperature recordings at the end of the trailer near the refrigeration unit. This pattern is also common when the product is loaded too high or when the return air vent is blocked.
  • Is there damage to the walls, ceiling, floors or doors?
  • Are there any gaps caused by damage to the door seals?
  • Are kazoos in place on the drains? Kazoos are the rubber devices on the outside of the floor drain tubes which allow water out, but block air.

Internal trailer damage

External trailer damage

STEP FIVE: Document any evidence that the doors were opened during the trip

  • Does the TempTale temperature graph show a sharp spike in temperature during transit? (not to be confused with defrost spikes)
  • Sensor graph showing temperature and light
  • If using a TempTale Geo, are there light sensor readings during transit?
  • Did the trailer stop to load additional product along the way?
  • Did the trailer arrive without the seal or with a broken seal? (Learn more at Cargo: Don’t Break the Seal posted by Great West Casualty Company)

We welcome your feedback and look forward to answering any other questions. Contact one of our Sensitech experts today.

Download the White Paper: 8 Imperatives for Supply Chain Excellence in a Time of Chaos

find-expert-bar-blue find-expert-bar-mobile