Bottom Line
Do-it-yourself climate control

By Jim Park
Special to Land Line


Go ahead and laugh. Other drivers did when they saw the room air conditioner hanging out of Al Morzuch’s passenger window. It was ugly, but it worked.

He’d park for the night, wrestle the unit out from under the bunk and mount it in the window, seal up the opening, and then go to sleep in comfort without running the engine.

 “I got lots of strange looks from guys walking by the truck. I tease them saying I plug it into the cigarette lighter. But, hey, when I tell them how it works and how little it cost me, that kind of wipes the smile off their faces,” says Al, an OOIDA life member from Interlachen, FL – about 70 miles southwest of Jacksonville.

The idea to run a small home air conditioner in the truck first occurred while Al was hauling boats. He was always around places that provided easy access to AC power, so he bought an air conditioner and plugged it in wherever possible so he wouldn’t need to run the truck to stay cool at night.

Next, he added a bank of four Odyssey deep-cycle batteries and a 2,000-watt Trace power inverter to drive the air conditioner when he wasn’t near an AC power source. Then he added a 1,500-watt portable heater and he was set: heat in winter, air conditioning in summer – all without idling. But he wasn’t finished.

His four-battery setup wouldn’t last the night, so he added four more and had a system that

worked – and didn’t burn a drop of fuel. He installed a 6,500-watt generator, as well, to guard against the worst-case scenario.

 “The generator is on there in case I ever need it, but I’ve never run it once,” he says. “With eight batteries, it’ll run eight hours easy at 90 degrees. If it’s cooler, it’ll go 14 hours or more.”

He admits the setup is a little heavy – close to 1,000 pounds – but his cost was a fraction of a store-bought APU or a battery-driven OEM climate control system.

The sum of the parts
Chassis weight isn’t a big issue for Al, but it would be for some. His big concern was running the system without burning fuel. The batteries are key in his case.

Others might want to consider a system without batteries if they’re prepared to run a generator. That would eliminate a great deal of both cost and weight.

Here’s what Al’s running presently: 

  • 5,000-Btu air conditioner from Sears, less than $200;
  • 6,500-watt used Onan generator from eBay, less than $400;
  • 1,500-watt heater from any hardware store, less than $50; and
  • Eight Odyssey Group 31, deep-cycle batteries at $350 apiece, or $2,800 total.

He recently cut out a section of the back wall of the sleeper and mounted the air conditioner permanently over the bed. In fact, he has added a second one for extra cooling capacity, but at 5,000 Btu – enough to cool a 10-foot-by-15-foot room, or about 150 square feet – he says it’s more than he needs

80 percent of the time, “but it comes in real handy on a hot sunny day.”

Al notes his system will pull the interior temps down to a comfortable range in about 20 minutes, but the key to maintaining it is extra insulation (see story at right).

 “The extra insulation in the walls and ceiling makes a huge difference in the battery life,” he says. “It halves the work the air conditioner has to do, nearly doubling the battery time. I also added a second layer of carpet on the floor and put cut pieces of foam over my windows to keep the heat and sun out in summer, and the heat in in winter.”

One of Al’s concerns going into the project was durability.

 “Those air conditioners weren’t designed to be bounced around in a moving vehicle, but it doesn’t seem to bother them,” he says. “I’ve had one in there for six years, the other for two years. No problems so far, but I don’t run them while the truck is moving.”

The physical setup
Al bought an extra battery box from a junkyard. He installed six of the deep-cycle batteries there, and two more into the original battery box, leaving room for four “starting batteries” in the original battery box.

Separating the two banks of batteries took a little thought. The problem was discharge.

The deep-cycle batteries would draw down overnight, and if the two banks remained connected, the starter batteries would draw down with them. He separated them at one point with a heavy-duty isolator switch – which preserved the starter batteries – but to charge the deep-cycles from the vehicle alternator he had to reconnect the two banks.

Current will flow from a good battery (the starter system) to a low battery (the deep-cycles), and that will produce a high current flow between them, taxing the alternator and the starter batteries.

The final solution was to install an additional alternator on the engine (which was surprisingly simple, he says) to charge only the deep-cycle batteries while driving; or he could use his generator.

He has cabled everything using 4-gauge cable, and crimped battery connections. He cautions other do-it-yourselfers to be careful when routing cables to protect them from chafing and rubbing, particularly where they enter the cab. “You need to grommet that area to protect the cable,” Al says. “That’s how fires start.”

As previously stated, Al’s big push was to achieve suitable climate control without burning fuel.

Battery capacity remains a challenge, as does creating a suitable charging system. Clearly, though, it can be done.

For the less inventive, or less mechanically inclined, two potential solutions to a factory system remain. The first would be an inverter generator (see story below). The second is an off-the-shelf 120-volt AC generator of suitable capacity – something in the 2,000-3,000 watt range – to power the appliances, coupled with an inverter to run smaller appliances while the engine is off and to trickle-charge the truck’s batteries. LL


Editor’s note: Jim Park is the former editor of Canada’s highwaySTAR magazine, and a founding member of the Owner-Operators Business Association of Canada. He spent 20 years on the road as a driver and owner-operator before becoming a journalist.