Air Conditioning/Inside the Pipes

We just spent a great 3 days at The Great Outdoors With our newest best friend Bill and while there realized another element of the OTR A/C that has, with other conciderations, made me decide to change my mind about that option.

The straw that has broke the camels back was when we realized for the first time, when getting a nickle tour of Jody and Bills bus, the normal baseboard at the bottom of the walls in a bus without it. We had no idea that if no OTR A/C, there will be no 1FT high by 5inch duct that runs all the way around the base of the interior walls of the bus. In this game when square inches ,where you can get them, are so important, and that, combined with all the other space issues that surround this option, in my opinion, make it too much of a compramise to make.

If I knew 9 months ago what I know now this is what I would have done. We would have gone with a large automotive style A/C compresser,for a drivers air only off the engine. We would have then either replaced our inverter with another large enough to power a cruise A/C or added a second indipendent inverter specifficly for that purpose. Either inverter setup i've proposed would have been capable of powering either the rear unit or the one mid ship building in some redundency. If and when the ambiant temps are such that 1 rear cruise air combined with drivers A/C off the engine would be insufficiant the gen. would then come on to run a third unit.

That would have given us the same comfort while at the same time doing it more efficiently, and giving us that all important MORE SPACE in the engine compartment, a whole nother empty basement bay and all that additional interior space that we have just learned about around the base of the walls.

Also if no OTR A/C the heat would come out at the floor where it was needed instead of at the bottom of the windows where you have to get the bus interior temp. 90 to warm the floor area acceptibly.

This proposed alternative solution might even cool the cockpit like we expected the OTR A/C to do but dosen't.

Well there it is for those of you still looking for a bus. My 2 cents. You can take it or leave it. This option will not be real high on the priority list if we ever replace our 86.

Very well put, Joe.

And as I began suspecting after I proposed the question to everyone, OTR A/C or Not..?

Most everyone agreed that OTR A/C was not worth the additional money, loss of bay space, HP loss, and therefore NOT something to look for in a coach, but something to consider only if everything else in that coach is what you are looking for.....!

Given the money I have spent on getting my Country Coach A/C working, which IS a glorified auto AC (but bigger) working, I would have chosen Prevost OTR in a heartbeat.

OTR in new coaches doesn't necessarily come up around the baseboard as you mention, but I believe at one point (mid 90's) it came up through the window panels, and many of the new buses, the OTR is piped in with the general A/C system.

One thing I have NEVER heard from anyone is that the Prevost A/C didn't work, and work well. Perhaps too well. But, I tell you when I limped into Las Vegas at 120+ outside the bus, and probably 140+ inside, I'd have given anything for Prevost OTR.

My two cents. As mentioned, your mileage may vary ....

The debate will go on but I like my OTR. It Vents thru the coffered ceilings,windows, & small vents incorporated into the backsplash in Kitchen and the two bath sinks. It returns thru slotted openings in the hall(at floor) between the Galley and Bath area. Keeps the entire Coach Climate controlled. The only down side I can see ; no speed control. One speed only on the two squirrel cage fans. Yes, I do not have two extra storage spaces but I am not taking my Golf Cart nor Harley with me.(Don't own them)
Country Coach has a 400 amp inverter & charger for their 2007 which allows you to run two roof A/C,s I believe. So, there are other good choices available.
Beats me what all the fuss is about. OTR was not on the top of my list for what I wanted in a Coach.

Might as well add my 2 cents to this thread. I have 97 Liberty with OTR. After spending over $2,000 in repairs and three trips to Prevost it's working great.

I was told by other Liberty owners that I needed the OTR system so that's what I bought. Drawbacks are the loss of two storage bays - Storage space is important to me as a full timer.

Ductwork along floor not really a problem as I have two sofas and they hide most of the ductwork except a section under the dinette table. In bedroom, ductwork along wall on passenger side makes it a little difficult to get arond the foot of the bed.

If I had to do it all over again I would opt for more storage, good cab air system and use the diesel Gen to run cruise air system while on the road.

Lee
97 LIberty 40' Classic

Despite all the blather that some converters have used to promote their idea of the best way to cool a coach I have developed some fairly strong opinions about what and why.

Remember, these are my opinions only.

I think the biggest arguments for OTR air are the ability to cool a coach quickly under any and all circumstances. Once a coach is cool, keeping it cool is less of a problem, but nothing matches OTR air.

If a converter converts a shell with OTR air the engineering and effort increases quite a bit. Without it you just install cabinets, walls and trim. With it you have to provide ducting and consider balancing air flow which is not as easy as it sounds.

If you do not have OTR, you probably do not want cruise airs. They will not work real well when trying to suck air over the condenser unit while driving because usually the highway is radiating some seriously high temperatures from the surface, and that tends to cost efficiency or even shut down the condensing unit on cruise airs. By going to roof airs you eliminate that problem and you are being consistent in addressing the biggest reason converters push their own version of air conditioning over the OTR system.

With no OTR or cruise airs you free up space behind the front bumper, some space in the center of the second bay, and some shallow space on both sides on the third bay. The net gain is probably the equivalent of a bay, but it is spread around the spaces described above.

There is sometimes an argument that OTR robs HP and roof airs or cruise airs run from an inverter do not. Not true. There are no free lunches and to provide the same amount of cooling when driving the load on the engine will be roughly the same, except in one case it will be a big compressor, and in another it will be an alternator.

Again, these are my opinions

Jon offered some good points about the Cruise Airs and there inability to work effectivly under extreem heat while motoring. Concidering my thread was directed at those who are still looking that was a oversite on my part when suggesting to opt out of the OTR

Because our bus does have cruise airs, it is probably better that we repaired the OTR A/C.

This Cruise Air topic, however, adds to my thoughts that if we ever move up the roof air units would be prefferable, in conjunction with drivers air only off the engine. We would not have the OTR A/C and going down the road the roof airs are not going to have a problem cooling. In addition they are easier to service, less expensive, more available when you do need one and frees up that additional space in the basement as well. For a 40ft bus 3 roof airs are going to cool it down pretty quickly in extreem heat. The only compramise in my opinion would be the looks and that is a compramise we would be willing to make.

Sure would have been nice to be a POG member before we bought ours.

Once your coach is converted it is going to be expensive switching AC sources. For example, in Joe's case he could physically remove his OTR and cruise airs, but unless he is prepared to run his generator while driving down the road, he has to insure he has inverter power to not only charge his batteries and run other things, but he has to be able to run at least 2 and possbile three roof airs.

For the record would someone please catoragorise the types of heat and air that you speak of in these posts. I think many names are for the same appliance.

If one has OTR/air does one have OTR/ heat?
Can you have one without the other?
If a bus is advertised as having bus heat will it also have bus air or must I ask?

Is bus/air one and the same as OTR/air?
Is bus/heat the same as OTR/heat?
If you do not have bus?heat where do you get your heat?

Is cruise air the same as roof air?

Do any of the rooftop units furnish heat?
Does Webasto heat go through the bus/heat ducts

Do the roof top units blow through ducts for a comfortable draft free environment, Or is it a powerfull drafty overhead stream?

If OTR/air is used while driving then when you require air when parked you must also have roof air,Yes? No? I don't think you get OTR/air when parked unless you run the engine?

Exactly how many heat and air source combinations are available?(relating to post 97 Liberty & Marathon conversions)? :confused: :confused: JIM

With OTR air you get OTR heat.

I assume if you do not have OTR air the bus still has a whole bus Prevost installed heating system. Can someone verify?

Bus air, Over The Road air are the same thing in the context of these discussions. Precisely it is a whole bus air conditioning system with the large Carrier (York) compressor, and the third bay on each side containing the AC condensing coil and evaporator coil. Whenver the engine is running the OTR air can be used for cooling, but if parked for any length of time the other systems are generally used powered by shorepower, the generator, or in ssome instances batteries.

Cruise Air is a brand name for an air conditioner that has a separate condensing unit (usually remotely mounted behind the front bumper and in the center area of one of the bays), connected to a remote evaporator unit, typically mounted in the living area out of sight but ducted as required. The condensing units usually draw air for cooling beneath the coach. When the bus is parked this is good because the air is drwan over a shaded surface. When the bus is moving, however that may pose problems because the highway is usually in the sun and is radiating heated air which may affect the ability of the Cruise Air unit to function properly. The Cruise Air units are closer to commercial quality and use heat exchangers and components such as might be found in commerical refrigeration products.

Roof air units are usually the same units as found at Camping World and which might be found on everything from a pop top camper to a conventional motorhome. They are inexpensive but will generally have the same output as a Cruise Air. Where the roof air units excel is they are getting fresh, cooler air when the bus is in motion, and they are inexpensive so repairs or replacements are cheap. Further, you can probably get one at most RV dealers.

Roof airs may be ducted, or may be dedicated to a specific area on a coach. That decision is up to the converter.Some roof units are provided with electric heat strips so in addition to cooling they can be used for heat. Both roof airs and cruise airs can be heat pumps which makes them suitable for coach heating and cooling down to around 35 degrees. The heat strips will heat at any temperature. Drafts and other issues are present with Cruise Airs or rooftop units and is dependent upon the converter and how they ducted and installed the units.

Webasto heat is another system, unrelated to the AC systems. Webasto operates by heating engine coolant which is circulated through not only the bus engine, but heat exchangers located throughout the coach and controlled by thermostats.

There are typically multiple environmental systems in our coaches. On my first Liberty I had OTR air and heat, and three Cruise Airs that were AC only. For heat I had 3 propane furnaces, four electric heaters (toe space low profile) and to supplement the bus heating I had at least four auxiliary heat exchanges that used engine coolant as a heat source.

The current Liberty has OTR, four Cruise Airs that are also heat pumps, two electric toe space heaters, and the Webasto system with multiple heat exchangers (at least 5). As you can see we not only have flexibility, we have backup redundancy and each source of heat or cooling has its optimum time for operation.

I hope other owners with differnet conversions will chime in here.

Jim,

Great questions that really hit on the confusion one encounters while shopping for a bus.

Jon,

Great answers that address your Liberty. It does point out that there appear to be any number of combinations that are controlled by both Prevost (on the original chassis build out) and then the converter.

For those of us hunting the used market it seems that the best we can do is accumulate a good understanding of each system, strengths and weaknesses, and then try to make a good decision. There really no right or wrong answer that I can see.

Were I to buy a bus with 4 roof airs and the standard "drivers heating and A/C system" I would have a couple of ways to heat/cool the bus. That may be the best that one can hope for ??

Michael

I would echo Jon's comments about the use of Cruisairs when running down the road. If you want sweat running down your Lewcrack, that is a good way to get it started.

To the rest of the conversation.........

Plenty of Storage Space - Way Good
Plenty of Cooling Capactiy - Outstandingly Good

I don't care if I can stuff an army of pigmys under the coach, if it becomes a sweat filled torture chamber while running down the road, no one will care how much extra stuff resides in the bowels. Living in South Texas, it is highly unlikely that I will own a coach without OTR air and that cooling has to comes from somewhere, so taking X many BTU's, however you get it there, will cost you something.

If someone wants to take the time to figure out all the energy / efficiency / cost numbers for using roof air / cruisair / Webasto / driver air / OTR air, then so be it. It just looks like a math equation to me and I am comfortable with the use of space vs having to have an onboard HVAC person to keep it all sorted out.

Thank you Jon, Very well done. JIM:cool:

Prevost Car, after many years of research, developed an over-the-road air conditioning and heating (OTR) system designed to keep 48+menopausal French Canadian women from complaining constantly.

Get the OTR.

And those fine ladies were on tour in Arizona in August.

Thank you everyone for organizing the confusion. I can see that, where, when, and by whom the bus will be used all figure into the equation. The coach and converters seem to have covered all bases. That leaves the decision up to the purchaser and the used equipment available at any particular time. :eek: JIM

What a GREAT CLUB:)

Jim

Opinions are like..... well you know the rest of that.:D

I like the Cruisairs and have had no problem while driving, although I rarely have to run one. I can run two going down the road off the inverters and haven't experienced the need to do that. I like the clean look on the roof, the highest thing on mine is the flat top dish that's about 6 inches tall.

I just had my 3 cruisairs checked for freon, there all behind the front bumper, and asked the Tech his opinion on roof or cruisairs. He hated the roof airs from a maintenance standpoint and preferred the cruisairs saying they were commercial grade in his opinion.

Mine is 40' and if I had OTR, my bay storage capacity would be ziltch. Also, the last thing you ever want to happen is someone at Camping World or some of these other useless RV repair facilities on the roof of your Prevost.:eek:

Part of the deal about heating and air conditioning systems is how they are set up and how you use your rig.

Our Angola had OTR and I thought it was overkill. Then, one afternon in some God-forsaken place, I think it was near Jamestown, NY, in late October, it was starting to sleet and the inside of the coach was getting mighty cold. We flipped on the OTR heat and were glad that we had it. Conversely, when driving in fundamentally hot environs, the OTR air is the trick to keeping the coach cool.

One thing not covered here is that if you begin the day with a cool coach it is a heck of a lot easier to keep it cool. Just a side note.

Our current OTR set up has rheostats (for Lew) for both the dash air and bus air. In addition, the temp is adjustable for each and you can set adjust recirculation/fresh air for the sytem. Further, with the warm/cool air running up through the walls of the coach from the baseboard exchangers, there is likely kind of a passive heating/cooling thing going on which is pretty comfy.

As to the loss of storage space due to OTR, it means that The Boss can't buy as much stuff along the way as she wants.

Everyone wins.

Boy you really konw how to hurt a guy. I was thinking of setting up my garage in Jamestown. It's not god-forsaken just depressed, with a lot of cheap realestate. JIM ;)

Thats the plan Imre, Thats the plan!! :D JIM

Quote:

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Originally Posted by JIM CHALOUPKA

Boy you really konw how to hurt a guy. I was thinking of setting up my garage in Jamestown. It's not god-forsaken just depressed, with a lot of cheap realestate. JIM ;)

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Are you talking Jimtown PA? There are some properties available in the Kinsman area that currently have buildings capable of housing a bus and only half as far for you to drive too.

I drove through Chardon (route 44) on my way to Painesville in December, WOW has that area built up since my last trip - maybe 10 years ago. Where'd all those people and houses come from?

Orren, It's Jimtown,NY. For my plan I need a garage close to lake Chautauqua to store the bus for the extended summer season. I don't want to leave it outdoors in some field without electric when we are at the lake.

Geauga county surely is getting built up and it seems there is a horse in every back yard. They say there are more horses in the county than people. I say there are more horses asses than horses! :D I can't wait to get out of here. I'm chompin at the bit!! :rolleyes:
JIM


[SIZE="1"]The next time through stop in I am usually home. 2169784440[/SIZE]

When I used to travel your area on a regular basis the only horses I saw were around Kirtland or up at Sidley's in Painesville.
My stepson is the pro at a golf course near Nunda NY. I know he has some barn space, but it's another couple of hours past Chautauqua (south west of Rochester). We're going to Florida in a week or so to visit him - I'll ask if he knows of anything available in the lake area.

We used to live for about 38 years in Jamestown, NY.

Property is cheap because taxes and utility costs are so high.

One of the happiest days of our lives was when we left Jamestown for Knoxville.

A year ago I had my OTR air changed from R12 to R134a. They flushed the system, changed oil, and replaced the seal. I was told the hoses would probably be OK.
Yesterday I had it serviced. I was told the condenser blower was too fast and if I could slow it down it would put out cooler air. Does this sound right?

Mark
1988 Vulcan XL

Welcome to the forum. I can not answer that question for you but am very interested how that freon change works for you in the comming years. We have R-12.

Quote:

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Originally Posted by mwalker422

A year ago I had my OTR air changed from R12 to R134a. They flushed the system, changed oil, and replaced the seal. I was told the hoses would probably be OK.
Yesterday I had it serviced. I was told the condenser blower was too fast and if I could slow it down it would put out cooler air. Does this sound right?

Mark
1988 Vulcan XL

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Mark, I think what the service tech was getting at was that the air blowing through the condenser (which is the part of the system that gets cold by the refrigeration process and cools the air passing over/through it) is moving too fast and not getting as cool as it would if it took longer to blow through it. [(slower blower, slower air speed) = more cooling.] If the fan is belt driven often times a (split) adjustable shiv (pulley) is used to adjust the RPM of the fan, or you can change the non adjustable shiv (larger or smaller diameter) to adjust the RPM,s.:eek:
Need more ask. JIM

Mark, Please show and tell us about the Vulcan XL! :) JIM

Mark: Is your OTR system a Carrier or a York system? In other words, do you have a Prevost OTR or a converter system, such as a Country Coach?

Thanks in advance.

Jeff
It is a Carrier from the factory. I had Thermo King convert it to R134a. He did not replace the dryer and that bothered me. It does cool but I think it should do a little more.

Jim
The conversion was done in Hueytown, AL by http://www.vulcancoach.com/
I Do not have any pictures on file but it is still @ http://www.rvsfsbo.com/show.aspx?adnum=58573
I bought it over three years ago and it is still listed.

Mark

I was going over some issues that I was dissatisfied with concerning the poor preformance of the drivers air with a service shop forman.

Our OTR system has only the 1 large 10 ton carrier compressor and the refrigerent lines are teed off at the condencer and flow from the main system to the second smaller evaporator for the driver.

It did not cool and I have found out that the temp. control valve for the heater core up there has worn and it does not close completly, and this is not uncommon on many older busses, so I'm told.

I clamped off one of the hoses to it manually to check it and shazam I'm now getting COLD AIR.

The culprit is located on the top of the spare tire bay.

I was adding some 134A to my bus cooling system and it sprung a leak. I located it at the condensor so it wasn't going to cool till I got it replaced.

We had a wedding in Lincoln and was taking the inlaws and a couple of grandkids so I wanted it to be cool. But that wasn't going to happen, I had to just run the generator for the day to keep the bus cool.

I took off the condensor and took it to the local radiator shop and they said it was shot. I had called Prevost just in case they couldn't fix it. Prevost said an aluminum one would be a little over $1000. and a copper one would be $2200, was this a shock! My local guy had a rebuilt one on the shelf for $90. I installed it today and will vacume the line tomorrow, if it holds, I will recharge.

Just goes to show you.....there's always somthing.

Dale,

Are you talking about the big condenser that is on the hinged door, passenger side?

Regardless of whether you have OTR or just driver's air how does a condenser get bad. I understand a fatigue crack that needs to be welded, but unless it has corroded from external elements they should be good for a long time. No?

Jon, I have drivers air and the condensor sits on the outside of the radiator. It looked like some salt or some chemical hit part of it and started to decay. I had an aluminum one and put another one back on. I think the copper one would be a better choice, but do they cost!

Dale,

Now I understand. Of general interest to all, we ran in the snow belt for years with our other coach. Salt either from the roads, or from the air if you live near a coast is a killer. I had to replace radiators from corrosion. The salt would literally eat the fins so bad they would crumble.

Now with 20/20 hind sight I realize that frequent gentle flushing with water periodically would increase the life span.

In our buses, it affects condensing coils, air to air intercoolers, oil coolers, radiators (bus and generator), cruise air condensing units and if near a coast, roof airs.

Just came thru Lake Mead and Las Vegas with 113 degree temps and interior temps of 95. Should 3 cruise airs handle this?

I replaced the insulation in the brow windows with thermal king duct tube wrap. That compartment really gets hot without some insulation up there.

I was wondering if we painted our buses underbellies white or silver if that would help with the road heat?

It was so hot in the coach that the kitchen tile was hot to your bare feet.

I saw two coaches at Circus Circus RV park both owners not at home (one Royal, roof air and one Marathon, bsement air) I was going ask them if there a/c were working OK.

GregM

Greg,

We were in Las Vegas last year and it was 110 and the Cruisairs kept up (1) when we were sitting still (2) with the awnings helping shade the coach and (3) with me tuning up the snapperhead girls for going in and out the door constantly. And the roof of our coach is painted white.

When we were in motion, the coach air was plenty good. Except for when we detoured around the dam and started up the other side headed to Winslow. Then I cut the OTR AC off and fired the Cruisairs up (with the generator running). It was look enough, but not nearly as cool as the OTR ac. As soon as we hit the summit, I reversed the whole thing and the girls started squaking about it being too cold, so it was okay.

Greg,

When you are sitting still the ground beneath the coach is shaded. That means it is not radiating heat absorbed from the sun. Because of that the Cruise Airs will work well. On the road however they are getting hot air radiating from the highway drawn through the condensing units severely limiting the amount of heat the condensing units can get rid of.

If they do work when going down the road it is generally because the temperatures are cool. Mine never worked when going down the road when the temps outside were 90 or greater and the sun was shining.

For those with OTR A/C heat:

1. If the ambient temperature is below 80 degrees, but your coach is warm from the sun on startup, don't be surprised to see your compressor light go in. It may do so intermittently for a bit. Don't panic as I did the first time this occurs. All this means is that the refrigerant is below 20 psi in pressure and as it warms up and the pressure reaches 20 psi, the light will go back to sleep. It doesn't mean you are burning up a $2300 part.

2. Whenever you check coolant, always make sure to run the engine completely up and beyond the thermostat kick in. In this way you can make sure to fill the heating coils in the coach to the proscribed level. If not, you'll find that when you do turn on the heat, it'll suck up the coolant into the heating system. Then when you start up again in the morning, the coach will go into automatic shutdown. Then you think you broke the motor, which is substantially more than $2300.

Been there, done it.

And Mango's Karma helps too.