Can factory installed AC units work with shore power or generator?

[heeranyi]

I just picked up a bus this weekend, whew long drive from Austin back to Nebraska. It's a mid sized bus and has 2 factory airs on it. Can these be eventually hooked up to a generator or electrical shore power? Or do I need to also install a roof air conditioning. I want to be able to be home and plugged into grid power or at a baseball game in the middle of summer and have air conditioning running.

[aridgedell]

not without some pretty major work. My bus has the same set up and I am thinking about trying to run one compressor off a belt drive electric motor from an air compressor and see how that works. I don't want to have to cut chunks out of my roof. do both your A/Cs work? Both mine were totally empty and I'm working on fixing ac hoses and recharging.

[joeblack5]

exactly what i want to do on Elfie.
I think it is very possible and also efficient. A stationary bus without the engine running can have a much smaller cooling capacity. Both the evaporator and condensor are then larger then required so they can run on lower temperature differentials and that will increase the efficiency of the refrigeration process.

Please post your electric motor progress. I will do to.

Later J

[cadillackid]

to properly spin those compressors you very well may need 10+ horsepower per compressor... some busses were built with those A/C units on a completely separate engine just so they could run when the bus was stopped...

at 12 volts something like a starter motor might spin one but at a huge amperage and a very hot motor..

120 volt motors you are likely looking at a pretty big physically big motor to spin one correctly depending on the unit... 12,000 BTU is somewhere around 1000 watts or a little more depending on the compressor... most of those bus A/C units are 45,000-60,000 BTU EACH.. you you may need 4000-5000 watts to spin one properly.. and then you are perhaps oversized for an insulated, parked bus..

spinning the compressor slow results in much less condensation of your refrigerant, and because the indoor unit fan is designed at a fiarly high CFM (12 volt).. you will likely end uo with very poor at best humidity control, or not enough refrigerant volume flow because of low head pressure and you freeze across the expander device..

your outdoor fans.. likely 3 of them each unit require 30-50 amps at 12 volts...

im sure it can be done but there are far more efficient ways of cooling a bus when its parked..

even your fancy RV's.. many prevost 1/2 million dollar coaches, have separate "dash" or "road" A/C from that of the parked A/C...
-Christopher

[heeranyi]

Hi there, I'm so sorry but I don't know much about a/c's or electricals. Looks like I'll have to install a roof a/c that is separate from the ones that run off the motor that was factory installed. I'll check on pricing for 30 amp shorepower, roof a/c, and a generator. I called the cummins dealership to see if I could get a price for a 4000 Onan generator and they said huh? You bought a school bus? They didn't give me the warm fuzzies they could add it to my bus. So for those of you getting generators, is the dealership adding it for you or the person is actually doing the conversion?

[Robin97396]

If you can get one of those pancake Onan generators out of a RV you'd be in pretty good shape. They're on Craigslist pretty often. I don't think you're going to want to pay dealer prices for a 4k geny.

[heeranyi]

Robin, hi, how would you know if the used generator is working and who would install it?

[Robin97396]

Generally speaking you'd hear and see it running prior to purchase. There seems to be an increasing number of RV dismantlers selling off parts from wrecked RVs. You may be able to get the dismantler to hang the generator under your vehicle for a set price if you can come to an agreement.

It's not impossible for you to install it yourself. I've installed propane tanks under the skirt before. It's good to do the work yourself so you can know your vehicle better.

I'm also waiting to find a 4 - 6k generator so I can run a relatively decent size AC while I cruze through the hotter states. The silent diesel type of generator. I don't have a basement to put it in so I'm going to have to hang it underneath. It's quite inexpensive for the materials to support items underneath, and it's good practice so you can fix things when you're on the road.

[cadillackid]

having a generator definitely has its advantages.. for one you can charge your bus batteries if you run them down... you can run things like electric impact guns, electric "air" hammer, bright lights, etc if you have to make a repair on the road...
-Christopher