Using a generator for A/C in place of a costly APU

16 Nov.,2022


Truck Electric APU

Given the sometimes high cost of state-of-the-art auxiliary power unit systems to provide in-cab climate control without idling the truck – complete systems can range from several thousand to more than $10,000 – alternative methods for doing the same abound among owner-operators. New York-based owner-operator Doug Hasner’s method cost him just more than $2,000 in parts and has worked well over the course of the past summer.

The biggest parts of the investment:

  1. The 400-lb. diesel-powered mobile DuroStar DS7000Q 6,500-watt generator by DuroMax Power Systems — purchased for on $1,700 via Amazon, Hasner says.
  2. A basic 10,000-BTU household window-unit air conditioner — $340 at Home Depot, Hasner notes.
  3. Holley electric-powered fuel pump plumbed into Hasner’s Cascadia’s tanks to supply fuel to the generator – around $200.

“I can buy five of these for a single APU,” Hasner says of the generator. While “I don’t like to say ‘disposable,’ should the generator decide not to work anymore, I can pull it off in five minutes and have another mounted up in the same amount of time.”

The 400-lb. generator is secured with 3,300-lb. working-load-limit ratcheting straps to the deck just behind his 2012 Cascadia’s high-roof sleeper.

The most difficult part of the entire set-up: “Cutting the hole in the back of the cab” for the A/C unit “and having it the right size so you can seal it well and it stays secure,” Hasner says. After fitting it, he adds, he “used silicone and sealed it all the way around” from the exterior.

And unfortunately, he had to do it twice. A word of warning about the generator: When starting it, he says, the initial power output is equivalent to “brown-out conditions” in a home. The window-unit A/C has “a capacitor that doesn’t like brown-out conditions. I’m in Terrell, Texas, at 116 degrees and left the A/C switched on before I started the generator. That killed it.”

But conveniently, of a fashion, 45 minutes later he was in a Home Depot parking lot installing a new A/C unit.

“I’ve seen expediters do this in Ford Transit vans or straight trucks,” he adds about the use of window-unit-type A/C. “A lot of them have the camper-style A/C on top of the unit. I’d have done that, but I’m 13’6” at the roof already.”

The solution works for cooling, paired with an inexpensive Espar bunk heater, also diesel-fired, for warmth in winter. “Working with the budget I have, I put in place something that works as well as an APU. It may not be as durable long-term, but it’s definitely easier to fix because everything’s off the shelf.”

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