Rooftop AC for 144' Sprinter Conversion

Oh yeah I plan on putting a solenoid between the house and engine batteries

Most RV's use either a Fantastic Fan or a Maxxair as a ceiling fan. Both can be set to turn on and off automatically with temperature. You only need one for a class B.

It's a really bad idea to have a direct connection between the starting battery and the house battery. Accepted practice is to have an isolator that allows both to be charged by the alternator but prevents the starting battery from supplying electricity to the coach. If you accidentally deplete the house batter(ies) you can still start the van. Also deep cycle coach batteries and starting batteries are made very differently and do not play well together.

There is a lot of info on van systems in the Sportsmobile website (www.sportsmobile.com) but you might have to dig around a while to find what you need. They will also do partial builds on your van if there are parts of the conversion that you are not comfortable with.

What gauge wiring would you guy suggest for this build?

Engine Batt to House Batt?
Inverter to fridge?
House Batt to accessories/lighting?

90 amps times 12 volts equals 1080 watts at maximum. That's not nearly enough even if the alternator always put out max amperage. A few lead acid batteries will put out even less amperage.

Advanced RV models have Lithium ion batteries rated at 400-800 amp-hours together with a second alternator that is dedicated to charging those batteries. That system or a substantial generator are the only ways that I know of to power an AC while underway.

I have a 2004 T1N Sportsmobile/Sprinter with a 90 amp alternator and a 120 volt air conditioner. I understand that with a heavy duty inverter I could run it while traveling. Additional coach batteries would be necessary to run it while parked. The passenger van probably has a smaller alternator to deal with.

Mine does have a EGR valve.

What effect does the EGR have on running dash air?

I think there is no EGR system in your van so running the dash air is doable as long as the van doesn't over heat.All brands of ceiling power vents have a thermostat version.

Well if the outside temp is to hot for a dog then I wont leave them in there. I may try some sort of auto-start for the van that would kick on at a set temperature as a backup. Rooftop fans would be temperature controlled, but I will just never risk it in hot weather. Just nothing fail-proof for the dogs in really hot weather without a shore line.

Any suggestions for a temperature controlled Ceiling fan that could run in any weather?

For several years we camped in a home-converted B-minus. This was on a short wheelbase ford van with tall top for standing head room. We had a 5000 btu AC unit mounted in the back wall of the top, and the cooling capacity was inadequate in hot weather. We never used it while driving(no generator)and it took forever to cool down the vehicle after stopping and hooking to shore power. These vans are not very well insulated, and even with added insulation, the heat gain in hot weather is severe. For the size van you have purchased I would suggest no less than 10,000 to 12,000 BTU.