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Old 01-18-2019, 12:00 PM   #1
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Mini Split While Driving

Pardon me if this has been covered, but I've read and read and not seen (or comprehended) the answer.

I'm about to gut my bus and want to ditch the two rear air conditioners and passenger heater. If I install a mini split (which would run on a genny while parked), can I run it while driving? I'm sort of picturing it wired to an inverter, fed by a battery bank, which would be receiving power from the alternator while driving.

Is this feasible?

Joe

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Old 01-18-2019, 12:20 PM   #2
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Hey Joe,

You should be able to run it while driving.

The challenge is that your bus "road" A/C is likely 50k-80k Btu. Your mini-splits are likely 9k-12k Btu.

Heating and cooling loads are much greater while driving than when parked.

I removed the road air from my first bus and installed two 12k Btu A/C's. Big mistake. Two 12k Btu A/C's were terribly ineffective when I was driving in the Southwest in the summertime.

Both A/C's running full blast. Wearing just a pair of shorts and having sweat running down like crazy.

My recommendation: keep the road A/C and avoid TX, NM and AZ in the Summer.....
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Old 01-18-2019, 12:30 PM   #3
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General consensus has been that running AC like that is ineffective who traveling down the road.
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Old 01-18-2019, 12:43 PM   #4
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I’ll mention this is a shorty. Living space is 105 square feet.

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Old 01-18-2019, 01:30 PM   #5
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Originally Posted by PNW_Steve View Post
Hey Joe,

You should be able to run it while driving.

The challenge is that your bus "road" A/C is likely 50k-80k Btu. Your mini-splits are likely 9k-12k Btu.

Heating and cooling loads are much greater while driving than when parked.

I removed the road air from my first bus and installed two 12k Btu A/C's. Big mistake. Two 12k Btu A/C's were terribly ineffective when I was driving in the Southwest in the summertime.

Both A/C's running full blast. Wearing just a pair of shorts and having sweat running down like crazy.

My recommendation: keep the road A/C and avoid TX, NM and AZ in the Summer.....
Aye its real hard to cool a bus going down the road. Christopher can tell you more than anyone about AC!
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Old 01-18-2019, 06:07 PM   #6
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Quote:
Originally Posted by TeacherJoe View Post
Pardon me if this has been covered, but I've read and read and not seen (or comprehended) the answer.



I'm about to gut my bus and want to ditch the two rear air conditioners and passenger heater. If I install a mini split (which would run on a genny while parked), can I run it while driving? I'm sort of picturing it wired to an inverter, fed by a battery bank, which would be receiving power from the alternator while driving.



Is this feasible?



Joe
To answer your question, yes, you can run while driving. Will it cool like the factory a/c, not as likely. Mounting the air handler above the driver's seat with some extra 12 volt fans blowing would probably be your best location.

I run mine off of an inverter and battery bank
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Old 01-19-2019, 02:00 AM   #7
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I would not recomend it. you can possibly do some damage to your compressor. Condensing units need a solid stable ground while running. To much vibration can throw the balance off the scroll..
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Old 01-19-2019, 08:47 AM   #8
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its pretty well covered.. as for damage.. thus far i dotn think anyone has damaged them.. i know david ran his going down the road all summer.. it wasnt cold in his bus but the units didnt get damaged..


im always a propnent of either a specially built A/C that can alter its capacity like Joeblack is doing.. (running his bus A/C off of a pony engine.. he can vary the capacity by varying fan speeds and engine speeds).. or have a separate road A/C and parked A/C..



minisplits are an excellent choice for parked A/C in my opinion. buy a bus with dashboard A/C for keeping the driver seat cool in summer..



my red bus has factory A/C as a hanging unit in the rear.. i completely went through that system and it gives me about 37-40 degree air even on the hottest days and im somewhat comfortable up front in the driver seat.. (its a 50k system supposedly)..



in my DEV bus I installed custom dash air.. and even before i fixed the fubar-ed factory floors.. having the cold air dash vents blowing on my kept me pretty decent on all but the hottest days.. that dahs unit is 25k.. and the rear unit right behind it is 40k.



-Christopher
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Old 01-19-2019, 09:40 AM   #9
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Like Christopher said, I ran mine all summer on the road. The only problems that I had were that it didn’t cool the cabin very well and that I had a flare nut loosen enough through vibration that I lost enough of my charge to render the unit unusable.

I’ve since recharged the system and after tightening the loose flare nut I found have had no problems.

In my experience, with the oem fans running, it would cool the driver decently well mounted above the windshield, but the rest of the family was miserable.

The master bedroom also could cool well since it is such a small number of cubic feet: 7’x7.5’x4’. With the curtain to the rest of the bus closed it can cool or heat quickly in pretty much any situation.

The very front and very back of the bus were the places to be!

I don’t have the tome and money to try to do more with over the road AC ATM, but have realized that up to the mid 90’s opening the windows is honestly the best method for keeping the whole bus comfortable in the heat.

If you have factory cabin air that works, I would think hard about keeping it. It is very expensive to replace and hard to substitute for.
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Old 01-19-2019, 10:57 AM   #10
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the big thing to remember is that a full size conventional bus... 11 windows with a dognose that has factory or dealer imstalled Air-conditioning will have roughly 120,000 BTU.. thats close to 10 TONS! in fixed-A/C terms.. now granted during conversion you are insulating and removing or covering windows, etc.. however you are not going t oget it down to where a simple 12k or 24k BTU is going to cool it... your personal car factory air is usually 12,000 at least...



the consensus on this form seems to be people love to remove "those ugly units".. and its really a personal preference.. my own ideas is why soend all this time money and effort building such a nice RV that you dont even have the simplest of features in which is A/C..



as david mentioned, adding it is expensive and takes a lot of effort.. ive done it.. more than once.. and will be building a completely retro-looking system for my 40 year old restoration bus.. but its getting easier and easier to find busses that have factory A/C.. when you find one... treat it like a unicorn and enjoy being nice n cool on the highway.. and install mini splits so you can enjoy being nice N cool after you get off the road..



front engine busses give you lots of heat.. windows down in a bus at 85 degrees outside driving into the sun is a **LOT** different than windows down at 85 in your car... frankly i love being warm.. ikm the guy that sits outside in florida in the summertime working on my computer till it dies of heat.. but I will say its miserable at those temps in a bus on the highway without air-conditioning..



Rear engine bus you are a bit better off as you arent bombarded by engine heat.. but you still have the large windshield to overcome the sunload..
-Christopher
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Old 01-19-2019, 02:46 PM   #11
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Thanks everyone. I’m going to assess each unit and probably keep one and get rid of the other. I’ll probably keep the rear unit. If anyone wants the one I remove, you can have it for free if you help me get it out. The likely unit to go is a Carrier, about 25” across.

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Old 01-19-2019, 02:57 PM   #12
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The one to keep is the front one unless you are trying to keep the unused part of the bus cold while driving..
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Old 01-19-2019, 03:01 PM   #13
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Originally Posted by cadillackid View Post
The one to keep is the front one unless you are trying to keep the unused part of the bus cold while driving..
Christopher
But it’s in the kitchen! Such a small space I figured the larger back one would do.

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Old 01-19-2019, 04:20 PM   #14
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the problem is you are cooling the back.. the engine and big windshield are upfront.. in my unconverted bus where i have no obstructions.. my A/C is in the back and even after completely revamping it to blow 37-40 degree air im barely OK on those really hot days driving into the sun... in fact enough so that this summer I'll be adding dashboard A/C to that bus up front..



those hanging units can be moved.. you just have to rewire, re-pipe, reclaim-and-recharge the freon.. so you could move it someplace more acceptable than the kitchen
or if being hot doesnt bother you, then you can yank it altogether and run with just the back one..
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Old 01-19-2019, 06:34 PM   #15
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Christopher,

How can I tell how many btu's of cooling the in dash air is? My compressor is an old two cylinder york, the same one used in International pickups in the 70's, and it is the identical unit on my 77 Mercedes 240D. Which just does the job in the car, so it would seem to be almost useless in the bus. I have not tried it yet and for now just adds one more complication. Therefore am leaving it off for now. Have two rooftop rv a/c units for when parked.
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Old 01-19-2019, 07:13 PM   #16
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so your 345 has the york on it? those are pretty high capacity compressors.. you can get 30k or 40k out of it pretty easily.. if you want more.. buy the york to sanden bracket conversion kit and install a sanden Enhanced HD7.



most often the limit om capacity is the condensor and evaporator not the compressor.. for instance the sanden thats in my busses is the same thats used on cars.. but on cars the coils are much smaller so the compressor has a lot of reserve capacity.. the laws of thermodynamics take care of not ruining the compressor from too small coils..



someplace is the displacement of those yorks and they arent bad.. they arent the best with R-134a compred to sanden but you could get enough to install a decent A/C.



I gutted out the driver heater box on my carpenter for the dash air... and installed a heat / cool coil in it.. so I have dashboard air..


couple pics as i was building it.. unfortunatley the photobucket debacle of the forum a couple years ago destroyed the rest of my A/C install pics..



my 1978 loadstar will get a Scout style A/C up front as that is what went into the Loadstars back then..


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-Christopher
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Old 01-19-2019, 08:00 PM   #17
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The 392 that was in there had the york on it. I am pretty sure the bracket will fit the 345 as well. Must say the bracket put the alternator in a place that had less then 90 degrees of belt on it and tended to slip easy. Much better alternator bracket on the 345. I am saving all parts for the a/c. Right now just getting it running again is the priority. I would like working dash air in time though. Do not know if the inside unit(evaporator and fans) is factory, or aftermarket.

Your comments make me feel better about using the York compressor. Thanks
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Old 01-20-2019, 05:33 AM   #18
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That sounds aftermarket ,although with air brakes the compressor had to find a new home vs a standard scout motor . So your bus had AC units in the back or a loadstar AC on the dash ?

There was a rare option offered on bus chassis by international which was a factory ordered and shipped and then dealer installed driver AC while the rest of the bus got none or another was installed by the body maker. The big thing about those York compressors is not to spin them too fast, but with their big pulley and the relatively low rpm of the 392 it isn’t an issue.. I’m assuming you won’t spin your 345 any faster than the 392 or cam it up where you run high rpm..

Back to the belt I thought n factory config the AC had its own belt or shared with the water pump and not the alternator... or did it once have a dual groove alternato pulley?

Once the temps get above 10 again I’ll go look at the belts on the loadstar and see how mine are set up
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Old 01-20-2019, 06:30 AM   #19
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No air brakes, this one has dual vacuum boosters with hydraulic brakes.

The bracket for a/c has the york on top laying on its side with the alternator under it. Dual groove pulleys, fan/water pump, alternator, and a/c all run off one set, then power steering on a single belt of it's own.

The 345 has dual belts for alternator, and fan/water pump. Then two more belts running the power steering. For now I am going to keep this set up. However it does have one extra pulley, so maybe run the york off that at a latter date? Not sure if a single belt would do. Sold the Mercedes and do not remember if that had one or two belts running the york. I do remember it took a lot of power, of course 60 hp in a car is kind of under powered. I did end up adding a turbo...
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Old 01-20-2019, 06:31 AM   #20
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Oh, no units in the back just air in the dash two small vents near the middle, then one each side round vent just under the dash
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