Depends on what unit you have. Typically, you have to have the key in the off position, and then you hit a button on the control box in the sleeper to turn the APU on. Depending on your settings, the APU might be set up to only operate within a certain temperature range.
Most will accommodate a 15 x 15 x 21 " unit. If no inverter, of course 12 volt. If u have an APU with a good sized inverter, u can get a compressor type unit instead of the thermoelectric variety
An APU, Auxiliary Power Unit, is used on a truck primarily for driver comfort. In order to meet EPA diesel emission requirements truck operators can no longer idle their truck engine while they are stopped for extended periods of time. An APU can provide heat, air conditioning and electricity for hotel loads such as microwaves, televisions and block heaters. An APU will consume less fuel ( about 1/10th) than that of the truck engine. An APU is a very broad term for a unit that may only provide heat, heat and air or heat, air and electricity. APU's that provide electricity must include a generator.
Either a faulty power generation unit, or a faulty inverter. Depends on specifically WHICH APU you have, as some have full power generation and HVAC, while others might just have an alternator which charges the batteries and leaves truck systems running off of the batteries.
It could be done. You'd have to shut it off if you had the engine off and didn't have an APU running, because it would drain the battery very quickly.
Auxiliary Power Unit
Amount per unit
I have yet to see an Walmart truck equipped with one.
Well...yeah, we've got it. They can set it up in two ways, depending on how your truck is configured. If you've got an auxiliary power unit, you've got two AC compressors: one on the APU, for use when the truck's engine is off; and one on the engine itself. If you don't have an APU, you just have the compressor on the engine. You'll also have two coils in your truck. One's up in the dashboard, like it would be on a car. The other's in the sleeper.
Apu comes from India.
Apu
Apu was born in India
To operate the truck heater itself would require one of the more complex systems, such as the RigMaster APU... a simple generator won't do this, as the truck heat is dependent on the flow and heating of engine coolant, which a detached generator won't do.Simpler APU units such as the ComfortPro use electrical coils for heat, and won't provide heat through the truck's ductwork.More specifics as to what type of unit you're looking to install are needed here before one could even begin tackling this question. If you want to stick with the KISS principle, a small Honda gas generator and some extension cords can run your block heater and something like an electric space heater. You wouldn't want to use anything which runs off the batteries, since there'd be no charging of the batteries unless you hooked up a charger.