Keep your cool: Transportation refrigeration unit maintenance tips
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Keep your cool: Transportation refrigeration unit maintenance tips

Jason Morgan is the content director of Fleet Equipment.

Transportation refrigeration unit maintenance tips Carrier

The summer heat cooks the blacktop. Truck seats and steering wheels are nearly too hot to touch. And the transportation refrigeration unit (TRU) is working overtime to keep the load cool. Now is not the time to wonder if you performed the required TRU preventive maintenance the last time the trailer was in the shop.

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“We do not recommend putting off scheduled inspections and maintenance,” said Scott Koch and Freddy Muñoz, Thermo King district service managers, “but some of the critical items that should be looked at include fluid leaks such as oil, coolant, and refrigerant. Any of these could lead to major component damage.”

To avoid that, your technicians and/or contract service providers need to follow the proper maintenance practices, drivers need to correctly perform daily pre-trip inspections, and you as the fleet manager need to stay on top of it all. So here’s your quick and dirty go-to guide for TRU maintenance.


What will put a TRU out of service?

“If not properly maintained, belts and batteries can put a unit in a critical state,” Steve Borini, field service engineering manager, Carrier Transicold. “Belt tension and condition should be checked per the manufacturers’ service schedule; Regarding battery life, if the TRU battery is tapped by ancillary systems that run in the background, such as a telematics module or other accessories, a drained battery condition can occur if the TRU sits unused for a brief period.”

“TRU’s stop and start frequently during the course of a day and a battery has a limited number of cycles,” Thermo King’s Koch and Muñoz added. “A good quality battery is required for TRU applications. AGM or FLA are both quality batteries. FLA batteries often have a life of 18-24 months. Many customers have elected to use AGM’s in TRUs and are incorporating solar to significantly increase the life of their batteries.”


“Many fleets are finding solar panel charging systems to be a great way to keep the battery charge topped off,” Borini added.

Thermo King’s Koch and Muñoz rattled off several other systems that could lead to out-of-service trouble if left unchecked.
• Starters and alternators: “These will be affected by the number of stops and starts a TRU makes during the course of day,” they said.
• Refrigeration system components: Check for software updates to ensure the unit is running on the latest software version. “This will take advantage of any enhancements due to software updates,” they advised. “Sensor location and grades should be checked periodically to ensure proper operation.”


In addition to the aforementioned common air, oil, fuel filters, fluids and belts maintenance checks, they also indicated that components that are overlooked during PM/inspections are unusual noises that need to be isolated and taken care of; think things like: bearing on motors, electric stand-by, condenser, evaporator and generator motors.

Pre-trip inspections are your first line of defense

It’s an easy thing to take for granted, but pre-trip inspections (PTIs) are a must. Sure you might hear some groans and calls of “it was fine yesterday,” but you need to be sure. A lost load is an infinitely larger headache than taking a couple of minutes before loading the trailer for a quick inspection. Even more so when that inspection is automated–both Carrier and Thermo King offer self-diagnostic, automated inspection features.


“In less than 15 minutes, a Carrier Transicold unit self-diagnostic PTI routine will conduct up to 17 tests covering hundreds of potential alarm conditions,” Borini noted. “The PTI checks electrical system continuity, engine high and low speeds, fan motor operation and refrigeration system valve operation, to name a few. The display module will indicate pass/fail results for all tests and any alarm conditions.”

Koch and Muñoz detailed Thermo King’s automated PTI offering:

“The automated pre-trip found in Thermo King equipment also checks multiple electronic component operations as well as cooling/heating operation.”

The comprehensive diagnostic checks take about 15 minutes and the pre-trip results show a pass/check/fail code.

“The cost in time for running a pre-trip versus the cost of a load loss acts as extra insurance,” they said. “Additionally, the pre-trip is done independent of the operator, so other work can be conducted during these 15 minutes.”


How can you be sure they’re being done?

Technology, of course!

“Utilize telematics such as TracKing to remotely monitor equipment location and health status,” Thermo King’s Koch and Muñoz said and noted that TracKing allows fleets to monitor and react to selected codes the TRU may generate during operation.

“Having visibility to codes at the fleet manager level, gives a different level of insight than was not previously available before widespread use of telematics,” they said.

Transportation refrigeration unit thermo king maintenance

“With the remote monitoring capability that telematics adds,” Carrier’s Borini began, “the ability to effectively manage refrigeration equipment while in transit is dramatically enhanced. Before a driver is even aware of a potential issue, a dispatcher using Carrier Transicold’s eSolutions system could get an alert and determine whether the issue is critical. If it is, the dispatcher can direct the driver to the nearest service center. If it’s not critical, the driver can be instructed to address the problem after the delivery is made. Either way, productivity is enhanced, and load loss is averted.”

TRU telematics doesn’t just impact unplanned service needs, you can also leverage it to stay on top of preventive maintenance to avoid potentially catastrophic service events by setting parameter alarms for PMs.


“As an example, a TRU can be set so that at 1,500 hours, a reminder can be given to both the driver and/or fleet maintenance manager that the unit is due for an inspection,” Thermo King’s district service managers duo said.

“Centralized monitoring via telematics can help build a comprehensive record of individual TRUs in a fleet, by tracking factors such as engine-run hours and other data collected by the TRU controller,” Borini said. “This information can ultimately help the fleet manage and coordinate the service schedule for individual units. With some service arrangements, a fleet’s TRU performance can be monitored collaboratively with the fleet’s TRU dealer for a more seamless handling of service matters.”

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