Mini Split Ductless HVAC Systems:
A less expensive alternative to a dedicated Auxiliary APU Unit is the Mini Split Ductless HVAC Systemwhich is normally installed in residential housing and small businesses
A 9,000 BTU Mini Split system that range in price from $500.00 to $1100.00 can easily keep your HDT conversion cool without the need to run your trucks engine 24/7 when using it as a stand alone RV on short trips or when pulling over for a quick lunch or short nap at a road side park.
Mini Splits are available as a Heat and Cool system or as a Cooling system only with very little difference in price between the two.
|From 5th_Wheeler (Jon):
I have a Hitachi 9,300 BTU cooling, 10,300 BTU heating Mini Split system for my 770 and it will be powered by a Super Quiet Yamaha EF30iSEB Inverter Generator which set me back approximately $2,100 with the remote start option which will allow me to start the generator from the cab of my truck.
My complete HVAC System including the Yamaha EF30iSEB Inverter Generator minus mounting hardware and electrical supplies set me back right at $2,700 compared to a dedicated APU which will set you back from $6,500 to over $11,000 dependent upon on the system you purchase.
Here's a good Write-up about Mini Split ductless HVAC systems.