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sprintstream's avatar
sprintstream
Explorer
Jul 26, 2015

Anybody using a 12v Air Conditioner?

My Class B Motorhome, like many I suspect, gets uncomfortably warm in the back while tooling down the highway during the summer. Passengers and my wife don't like it. I've run my genset and my roof air conditioner to help out but I don't like using up my propane for moving AC. I prefer having full tanks for the genset when needed. I also don't like bouncing around a running AC since I've had problems with stuff shaking, bending and moving.

I've seen many semi trucks with the auxiliary units mounted behind the cab and from what my truck driver son tells me those who have them like them. I've seen some advertised for big boats but I've done a bit of searching and found no one who uses one in their motorhome. Our big 80 amp alternators should easily handle the load through the auxiliary battery system.

Has anyone done this or tried or done more research than me?
  • fitznj's avatar
    fitznj
    Explorer
    Jul 26, 2015
    I've had 3 vans (conversion/passenger) with the auxiliary AC units in the
    back. Essentially run extra cooling lines to a self-contained cooling radiator and fan. Quite a small unit which does a great jopb of keeping the rear cool.

    This is standard equipment on 12/15 seater vans. Call a junk yard and see if they have any laying around.

    Gerry
  • sprintstream's avatar
    sprintstream
    Explorer
    Jul 26, 2015
    I like the idea of the added evaporator in the back using the heavy duty optional engine compressor. Also very pricey but about the same as some of the 12v systems. I believe I'm going to keep my eyes out for a used or salvage kit.

    It's interesting that no one has added anything to help this problem. thanks for the input.
  • boogie_4wheel's avatar
    boogie_4wheel
    Explorer
    Jul 26, 2015
    Vulcan Rider wrote:

    The semi trucks don't have 12 V battery systems; 24V minimum and maybe 48.


    They are 12V systems. Batteries can be larger, but that depends on the chassis. Our International used 3 car-sized batteries.

    Military has (had?) 24V power. The lighting was still 12V (peeled from 1 battery), but had 24V starters, alternators, glow plugs.
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Jul 26, 2015
    You can add a second alternator. Its an option on F350 trucks.

    you can change the 110a alts to twin 140a and have plenty.

    There are kits on Ebay. I would not add a 12v AC. Cheaper to buy a 5K watt inverter and run your existing ac off the alternaters.

    Entire project under $600.
  • Vulcan_Rider's avatar
    Vulcan_Rider
    Explorer
    Jul 26, 2015
    sprintstream wrote:
    Our big 80 amp alternators should easily handle the load through the auxiliary battery system.


    I suspect two things here:
    The semi trucks don't have 12 V battery systems; 24V minimum and maybe 48.

    It's not practical because.....the entire output of an 80 amp, 12 volt alternator only produces 960 watts; not enough to run a very big A/C unit.
  • Dr_Quick's avatar
    Dr_Quick
    Explorer II
    Jul 26, 2015
    Years ago for the "Conversion Vans", they would put in an auxiliary unit to cool the rear of the van. I had a Ford 150 van that I installed a rear unit in it. Ran off same compressor as the in dash air. I mainly consisted of putting "T" fittings in the supply and return lines for the AC and running hoses to the rear of the van. I installed the unit under the rear seat and ran ducts to four locations.

    I found one Web Site for you for installing Heat AC to a van. https://www.discountvantruck.com/rvvanrearairconditioners/rvvanconversionrearac.htm

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