The nuts and bolts of APUs

How to select and maintain the appropriate auxiliary power unit (APU)

More details on diesel-fired heating systems, which can also be paired with other HVAC technologies for a more complete heating and cooling package, can be found at and

Temperature control performance requirements for APUs

The Technology & Maintenance Council, in its Recommended Practice RP 439, establishes minimum performance criteria for auxiliary power units used on Class 6 to 8 day cab and sleeper cab tractors operated within an ambient temperature range from -10°F to 120°F.

In general, these criteria state that after a tractor's engine is turned off, an operating APU should maintain, at a minimum, the following HVAC performance:
• Cooling - A maximum cab or sleeper temperature of 78°F for 10 hours.
• Heating - A minimum cab or sleeper temperature of 68°F for 10 hours.
• Perform as such for at least 10 continuous hours of operation as mandated by the original 2004 Hours of Service (HOS) rules and all subsequent updates.


Truck anti-idling regulations

More and more localities, municipalities and states are enacting anti-idling laws to reduce emissions and noise levels. Often, these regulations, and their penalties, are inconsistent.

At present, 28 states have one or multiple regional anti-idling regulations. They are: AZ, CA, CO, CT, DE, D.C., FL, GA, IL, MA, MD, ME, MI, MN, MO, NC, NV, NH, NJ, NY, OH, PA, RI, SC, TX, UT, VA and WV.

The American Transportation Research Institute, a transportation-related research organization, maintains a compendium of current idling regulations by state.

It is provided for free in two different PDF formats - the original compendium listing and as a foldable cab card for quick reference.

These can be found at


Where to find funding opportunities

Various federal, state and nonprofit organizations provide funding and incentive opportunities for the reduction of emissions from long-duration truck idling.

Among the states offering such programs are California, Oregon and Pennsylvania. Federal agencies include the U.S. EPA, U.S. DOT and U.S. DOE.

Details on these and other idling reduction incentive and funding opportunities can be found within the EPA's SmartWay website:

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