Who doesn’t wish that they could get better heating and cooling from their APU or battery powered anti-idling unit? Those of us with large sleepers and dark paint know that when the weather gets hot, their APU is going to run 24/7. My friend Gary posted some great tips in the forums about how to give your HVAC a boost.
I purchased a Pro Heat APU last year. I have a black Volvo 770 so it takes a lot of air conditioning to cool it off, the sun is not my friend in the summer. I have been in the Pro Heat shop a few times and have always asked if there was anything I could do to improve the performance of the air conditioning. Always the same answer, no.
If I was in 90 degree heat in the sun the Pro Heat just would not do the job. Even with the curtains closed it could not keep the sleeper cool.
One day my brother in law (Joe)was over to my house and had remembered me telling him about the problem he asked if he could take a look, he is trained in heat and air conditioning . Within five minutes he pointed out what he thought the problems were.
1:On the install they had cut two, three inch holes for my cold air return when the Hvac unit has a twelve inch by twelve inch opening that it draws from. My Hvac was starving for air.
2:The air ducts were routed through my tool box area and were not insulated. Joe said that I was losing a lot of cooling btu’s through the walls of the ducting system.
3: Joe pointed out that on my set up they had cut a hole in my existing truck duct system and just stuck one of my APU ducts in there and that again I would lose cooling btu’s by having to cool the duct system and that the cool air would naturally fall back into the truck a/c unit. Also, the way they just stuck the APU duct into my truck system the truck system had been partially blocked which decreased my truck a/c performance.
4:Joe pointed out that even though the truck has electric shut off valves on the input to the trucks heaters that there is always back feed which will put some warm water from the engine back into the truck heaters making the cab harder to cool.
So, I purchased a roll of four inch insulated hose from Menard’s $28.00 bucks and just slid it over the factory three inch APU hoses.
Then I pulled the APU duct out of my trucks ducting system and made a new vent for it then patched the truck duct. The new vent cost $6.00.
After that I went to the hardware store and bought a standard twelve inch by twelve inch return vent, Where they had cut two tiny three inch cold air return holes I cut an eleven inch by eleven inch hole and covered it with the vent I had purchased at the hardware store, cost $10.00.
Finally I bought two inline valves and installed them in both the input and output of the truck heater. Cost $10.00
The result… Well, I am in Richmond,VA it is 91 outside and my truck is sitting in the sun. Before I made the changes Joe suggested the Pro Heat would never shut off and would not keep me cool. Now, it cycles as it should, shutting the APU off when the cab temp is down to my desired temperature. Then it starts back up when the cab warms up.
What surprises me is that this multi million dollar company goes through so much effort to build a good unit, then does not properly install them to work up to their potential.
Happy APUing