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Dual Evap 1 comp A/C Design Questions

kamoo on Sat July 10, 2010 3:27 PM User is offline

Year: 1992
Make: Ford
Model: B700
Engine Size: 5.9
Refrigerant Type: 134a
Ambient Temp: 85
Country of Origin: United States

I was hoping someone would have some insight for me. I have an older school bus that I am selling but during the summer everyone wants A/C. Anyways, it has a Cummins 12v with the option of lower pass mounting or upper driver mounting, both will take a Sanden sd7h15.
I have two inexpensive 22k btu evap units. I know they are a little small for the application but my budget is a little small too, the other option is 2 roof mount 120v units with a genset @13.5k btu ea. I dont really like having a seperate power unit though. This bus will not be used for stop and go, mainly for 1-2 hr trips here and there.

I am having a little trouble determining the best way to set this up using one compressor. I can fab a skirt mount condenser setup with elec fans. One evap will be mounted in the front and the other a few rows back on the opposite side of the bus to try and keep the lines from being too long. I can wire it so that both evap fans will be on at the same time to avoid issues with that. I don't have a ton of experience with a/c systems but would really like to learn and don't mind making mistakes along the way, sometimes it is the best way. I know it sounds stupid to the experienced guys but you have to start somewhere, this is the platform I have.
When it comes time to charge, I do have a vac pump and gauges but will need some pointers if charging this would differ from a car.

Does anyone have any pointers?
How do you properly size the condensers needed, where would you get them? Can you plumb a few universals together that can be obtained at ackits?
Proper fan CFMs?
Where would you obtain an appropriately sized drier?
What size lines on the suction and discharge?

Thanks for everyones help

bohica2xo on Sat July 10, 2010 9:04 PM User is offline


Two evaporators. Two compressor mounting points available. Huge vehicle...

Mount two compressors, build two systems? No oil return issues, twice the compressor capacity. Seems like the most direct answer.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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