Driver's A/C

[Skykingrob]

When I gutted my coach, I removed all the OTR except for the driver's evaporator. I found out from Dayton Air, the manufacturer, it is 39K heat and 45K A/C. I am looking for a way to power the AC side of the evaporator. I can go the traditional route with an engine driven compressor and all of that. However, I was wondering how crazy it would be to use the compressor side only of a mini-split unit to power to evaporator. It would have to run off the 110 volt AC side of the coach inverter since it would be 110 volt. Most of the low watt use compressors are "inverter" models. I don't know if the "inverter" model can itself be run off a 110 volt AC inverter or not. Can they? All of the compressor units are to tall to stand upright in the spare tire compartment under the drivers seat, so the compressor would have to lay down and a hole cut in the floor to exhaust the hot air. The hole is easily doable but I don't know if the compressor can be layed down or not. Can they? I know the mini-split compressor units are more expensive than the engine driver compressor, etc. but it seems like there would be less work installing it than running all the hoses, etc for the engine driver compressor.
Thoughts?

Rob
91 Prevost
Missouri

[Jon]

I seriously doubt if it would be worth the risk to have zero back up. If you have engine driven AC, and it is supplemented with inverter or generator powered roof airs or mini-splits then if any one system fails you can still drive down the road with some air conditioning.

I admit to being influenced by years of flying and having as much redundancy as possible, but I have done the same in my coach to the maximum extent possible figuring how to deal with failures and what my back up plan will be.

If you ever drive into the sun, in the summer, in the south you will understand why I place such a high priority in having multiple options for air up front.

[Skykingrob]

Hi Jon
My fault for not mentioning this in my post but I have 2 coleman ducted basement airs as the primary a/c source. The front duct runs completely forward with a vent infront of the driver and one infront of the copliot seat. The setup I am thinking about is a "separate driver's air" and as such would be supplemental or backup as the situation would arise.
Thanks for clarifying.

Rob
91 Prevost
Missouri

[TomC]

About the most BTU that you can get off a 120vac compressor is 15,000. Since the evaporator is rated for 45,000btu it will not cool properly. This is why most power the driver's air off an engine run compressor. A mini split or portable cannot be run on it's side. They are designed to be standing to facilitate the oiling of the compressor. "Running all those hoses" really isn't as hard as it seems. Then you'll have a nice, powerful A/C. Just have to install the condenser somewhere-usually in the engine compartment so you don't have all the high pressure hoses coming up to the front.

I have three roof airs with the front one mounted up close to blow right on me in the driver's seat. I also have a dash mounted fan that blows on me. Between the two, they keep me cool-and I've been in up to 108 degree weather. But-I have to run the generator going down the road-burns about 1/2 mile per gallon. Good Luck, TomC

[Jon]

I thought that you would have some sort of 120V AC in the coach, but that will make the one you are considering 120V also. As long as you have redundancy for the 120V power that makes sense. Some coaches that run 120V devices through inverters do not have by-pass provisions if an inverter or inverter relay should fail and they have no way to get shore or generator power to the devices.

On the store bought coaches some conversions for example did not provide a simple bypass means so if an inverter fails and the refrigerator is on that inverter they are in trouble. The same would apply to your air conditioning concept.

[robertglines1]

I have a mini-split condenser stood upright in the spare tire compartment.   The evaporator would fit where the stock defroster/drivers ac etc is now.  Fwiw.   Bob

[luvrbus]

One is only kidding their self if you think you can replace the dash air with a roof top or mini split buy your self a 28,000 btu RedDot or other brands and enjoy the cool ride one good dash unit will put out more BTU than 2 roof tops or the splits 

[robertglines1]

Did not say it would. Just said it would fit.  I have both.  My split is above driver window built in cabinet.  The problem I see with conversion is high pressure of 410 refrigerant compared to bus  pressures.  Just a theory question.  No argument here. Enjoy the ride.   Bob

[luvrbus]

I keep hoping one of you guys Bob will try the DC/AC units like are used in emergency vehicles that should work good in a bus one would think I wonder what freon they use lol nothing beats a good dash air IMO

[Jon]

Sorry Clifford..........nothing beats full coach over the road air. Current versions have 109,000 BTU. My 87 had about 84,000 BTU. I'm sure dash air is good, but unless a person is happy with a heat soaked coach when they stop, or are willing to start the generator and run all house AC units whole coach air is the way to go.

[luvrbus]

I have to agree Jon but the road air has been long gone on most of theses older buses,a dash air IMO beats the hell out of roof air trying to stay cool when on the road  

 I removed my over the road air in my Eagle I shortly realized that was a mistake here in AZ lol I bought a Red Dot 38,000 btu for the front I never installed it the conversion was already finished and would have required tearing it apart again 

So I bought ear plugs to keep from hearing the wife and her thoughts on riding in a hot bus now I hear it from Matt lol

[Jon]

So I bought ear plugs to keep from hearing the wife and her thoughts on riding in a hot bus now I hear it from Matt lol


Good one. She don't read these forums does she?

[luvrbus]

No she doesn't read this board but some of her friends on FaceBook will tell her   and the I Pod worked good too till it quit

[robertglines1]

I feel your pain. Once said !  The comment that is.  My Judy is use to it.::: Most home converters that do not have the $$ to maintain busair do offset it by doubling insulation and better windows. I did have a ac unit in last coach aimed at drivers compartment and do have one above driver now.  I do try to make that area redundant with two means of ac.  A band of tint above drivers view helps cut down on sun heating thru massive front glass area. Also remember that heat rises to the top of your coach so any thing you can do to mix the air up will aid in your comfort.  A fan directed to mix air flow top to bottom. Cold feet and a hot head are no good so why not mix air and have a more even temp--degree F --that is.    Enjoy the adventure.  Bob

[robertglines1]

Original   You could do it.  The original evap prob would not handle the 410 pressure and you would need to use the evap etc that came with the mini-split system.  Also the compressor is the only part of condenser unit that has to stay upright. I have a 12000 btu unit mounted in the spare tire compartment. I did not modify it. The motor driven unit would be a higher capacity.  Would not give you heat and air while parked.  So as in anything in busnut world do it your way.  Bob

[Jon]

I am surprised by the number of folks that keep repeating they don't want or have removed full coach air because they don't want the expense of maintaining it.

My first coach was 17 years old before I had to replace the compressor which at $2100 equated to less than $130 per year. My second coach was 15 years old and my total maintenance was to replace one lazy circuit breaker. The current coach is too new to even talk about service costs.

Then I hear about how it takes 30 HP to run it. And that costs mileage. Bull and Bull. First once the coach gets to temperature it cycles on and off so even if it took 30 HP to run it it would be 30 HP times the percentage of "on" time. The cost of mileage is an argument that always compares apples and watermelons. Those who talk about mileage never ever want to recognize that to do so we have to talk about comparable conditions. Lets say my OTR keeps my entire coach at a constant 75. (I like it at 70 degrees and I am not happy unless my windows are fogging on the outside) For any discussion about mileage to take place the alternative to my OTR has to also do the same. That means from my bedroom to the dash my coach and every surface in it is 75 degrees. If the debater wants to apply logic their coach has to run enough air conditioners plus dash air to keep every surface in their coach at the same 75 degrees and depending on outside temps that might mean running 3 roof airs plus dash airs. Or in the case of a lot of coaches they just have to accept higher temps.

The fuel to drive the generator or the alternator which is powering the batteries which are powering the inverters use energy and energy is energy is energy.

Bottom line..........I just don't get why there seems to be so much negativity against OTR and it isn't limited to homebuilders. Those that drive the shiny $2.200.000 coaches are not equipping them with OTR and then in the southwest summers they either have to fire up the generator and run all the house AC units, or suffer in heat. I don't get it.

[RJ]

Jon -

Your points are all valid and well taken.

However, all are void when you park the coach and sleep in it overnight somewhere. 

Nobody wants to be parked next to a coach that's got that big old Detroit on fast idle to cool it's occupants at Oh Dark Thirty.

Thus the compromise of folk pulling OTR HVAC in favor of rooftop carbunkles or basement air units that will operate off either the quiet genset or the power pole.

The trade-off is less cooling on the Interstate, but quiet comfort while parked.  The "hidden benefit" is the acquisition of some additional basement storage space. . .

The high-dollar conversions often have both OTR and carbunkles, best of both worlds, with some additional maintenance expense to keep both systems operational.  Gotta pay to play.

FWIW & HTH. . .

 

[luvrbus]

Now that one I don't get Jon people paying a million plus for a coach and won't spring for the 20 k plus for road air my doctor did that one time never again then 20 grand is more than some pay for a coach

If you had a old coach that the up keep on the road air that has been neglected over the years there is not hardly enough cash around to keep one running that is why most lose the road AC a leak will cost you 1500 bucks to have one charged that is 3 roof airs for a conversion

[Boomer]

I mostly agree with Jon.  Coming from experience running revenue coaches, some old and some brand new, it is expensive to properly maintain the coach AC.  But once you get the systems up to snuff it is relatively easy to keep them in good shape.  We operated in 100+ temps routinely in the summer with our MC-9's and the 9 AC is greatly taxed and must be in perfect condition to keep the coach cool.  You are doing very, very good to lower the cabin temp to 25 deg. below ambiant.  Having to run 134A did not help matters.  The new Prevost's were never a problem and just had to be maintained by the book unless something failed.  One key is keeping that condenser and evaporator core CLEAN in any coach.  If a converter or new owner is trying to rehab an old bus AC system, expect to spend some big bucks.

[Jon]

RJ,

My OTR is solely for use when driving. When I am parked I have 4 Cruiseairs that I can power from batteries through the inverters (not the smartest thing to do, but possible), the shore power or my generator.

I would never suggest using OTR except when driving or when all else fails.

[mikelutestanski]

Hello.  My dash air system is a split system utilizing the dash evap with anew 134 exp valve and an 17900 btu red dot evap located in the kitchen cabinetry. The condenser is red dot 39000 btu located on the roof at the rear.  The compressor is piggybacked over the blower motor with a pulley bolted to the blower pulley.   The hoses and copper runs through the center aisle and splits to each evap.  The original evap with r134 is only good for about. 9000 btu and the other is 17900 so the front rooms of the bus have approx 27000 btu . We have been pleased with the results.  The cost was about $2650 for the whole system including some extra tools .
      Putting the system together  utilizing the cleanest and best work practices is necessary to end up with a dry leak free system.
      Regards.  Mike.  FWIW

[belfert]

My OTR air was totally shot when I got it.  The drier had a plug in it that was gone and all the refrigerant was gone.  I talked to a shop about fixing it and they quoted $700+ just to vacuum the system and recharge it.  When I removed the condenser I found that most or all of the condenser fans were shot which is probably why the system had blown the plug in the first place.  Dina didn't really make the condenser fans to be serviced.

The other reason I didn't fix my OTR air is because Dina ducted the A/C through the overhead luggage racks.  I would have had to use up a lot of valuable space ducting the air through the bus.    The condenser also took up 1/3 of one of my luggage bays.  I used that space for my generator after I pulled the condenser.

[Skykingrob]

I am reading the posts. Thanks for the responses so far. I did not keep the system b/c it was barely working when I got it. I spent $800 for 12A freon which mostly leaked out in a week, so I sold the whole system to a tour operator who paid we $3k for the system minus the evaporator. I think I got a great price for it. I am just trying to use that cash wisely to replace it with a "better system". Still looking for more a/c guys to chime in about the feasibility of what I am proposing. Nick, other a/c guys, you out there?
Bob-what is the brand name and model number for your unit?

Rob

[robertglines1]

Soleus  12,000 btu inverter type.  heat and cool.  I'll take pic in next couple days of condenser stood up in front spare tire compartment.  Pic of inside unit in bus projects topic section-- Above driver.  I thought about putting it under dash for awhile.   Bob

[Jon]

Whatever method to cool the coach is selected remember it is all about numbers.

A sitting coach can be comfortable with 30,000 to 45,000 BTU if it has good insulation and you take steps to avoid solar heating by keeping the shades down for example. But when you are driving at 60 MPH that same number of BTUs is inadequate because you have the wind wicking away at that cool air. The same is true in reverse for heating. Our windshields and side windows keep us hot in the summer and freezing in the winter.

A lot of store bought converters do not use OTR for the same reason Belfert has an issue with it. Ducting it properly to provide balance and air flow is very difficult and requires a lot of skill to get it right. But the same thing is true to an extent with roof airs or other type systems because in addition to having ample cooling capacity the air flow has to be directed in such a way to cool the entire coach evenly. If the cooling capacity is inadequate or marginal one rule to observe is to never ever allow the coach to get heat soaked. It will never get cool if air is only cooled up front in the driver's area. When you stop for the night and want to be comfortable 45,000 BTU will take forever to get a 90 degree coach and its mass of walls, floors, furniture, windows, etc down to a comfortable temperature.

The only other solution is to provide an excess of cooling and figure a way to move a lot of air.

[Hard Headed Ken]

Here's what I did for dash air. I think another important job for the dash evaporator is defogging the windshield.

http://www.busconversions.com/bbs/index.php?topic=24326.msg266755#msg266755

Ken

[luvrbus]

Jon, I give you a A for effort but you are preaching to the choir living in the AZ heat I know what a heat soaked coach is for sure about any AC works in 80 to 90 degree weather try 118 or 120 that take a Clydesdale  

Our dash air on a 1997 Vogue would cool about the first 6 ft of the coach in the drivers area the rest was miserable without running the generator  

Peggy at Vogue sold me a bill of goods telling me factory road air wasn't needed then I turn around and do the same thing on my Eagle but the problem with the Eagle it was ducted through the floor  


good luck