Trailer Refrigeration Units

Proper TRU maintenance

In contrast, a TRU operates behind the driver, with the only visual indicator being the status light mounted to the corner of the trailer and visible in the rear-view mirror. If the status light alerts the driver to an alarm condition, stopping for a visual check of the control display will reveal what is happening with the TRU.

The informative displays of Carrier Transicold’s Advance microprocessor and new APX control system, by way of example, provide text descriptions of problems rather than only numeric alarm codes.

A message may be something critical, such as a “Low Fuel Shutdown,” which is a forced shutdown due to an easily remedied low-fuel condition, or “Battery Not Charging,” which may require an alternator inspection. Or, it may be a more benign warning, such as “Check Coolant Temp,” a situation that warrants attention at the end of a trip.


TRU controllers themselves have become much more intelligent over the years. Each new generation of microprocessor-based controllers has provided a significant step forward in reliability, improved capacity and control and diagnostic capabilities that result in maintenance benefits.

Sophisticated controls can reduce capacity in operation, based on ambient and load conditions, thus reducing engine load and helping to prolong the life of the engine, compressor and other critical components.

Although they are no replacement for the experience, training and the well-tuned ear of a factory-trained service technician, the controllers on today’s TRUs speed up the process of diagnosing problems and can often lead a technician directly to the point of trouble.

Today, many reefers are equipped with telematics – satellite or cellular communications systems – that provide owners with the ability to monitor equipment location and operation. Telematics can also provide maintenance benefits through automatic notification if a refrigeration unit in transit is experiencing a problem, enabling the dispatcher to alert the driver as to the nature of the problem and whether it needs immediate attention or not.


The key rationale for maintenance on a refrigeration unit is the same as the importance of maintenance on a truck - reliability. The more disciplined an owner is in adhering to a schedule of service and preventive maintenance, the better the reliability of the equipment.

Reliability helps avoid over-the-road and after-hours repairs, as well as load-loss claims, the expense of which can easily eclipse the cost of proactive maintenance initiatives.

A commitment to proper maintenance also helps ensure equipment longevity and a lower cost of ownership over time– savings that can go straight to the bottom line.

John Jameson is the program manager of Comprehensive Maintenance and Repair Agreements (CMRA) for Carrier Transicold’s Aftermarket Solutions group in Athens, GA. Carrier Transicold helps improve transport and shipping temperature control with a complete line of equipment and services for refrigerated transport and cold chain visibility. It is an industry leader, providing customers around the world with the most advanced, energy efficient and environmentally sound container refrigeration systems and generator sets, direct-drive and diesel truck units and trailer refrigeration.

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