Air Conditioning/Inside the Pipes

[Just Plain Jeff]

The air conditioning system life and the most efficient use of air conditioning depends upon the chemical stability of the refrigeration system itself, to a large extent. The most widely used gas used in modern systems is R-134a. It is very important for all materials in the refrigerant system be chemically compatible. The only suitable compound for use with 134a systems is PAG, Polyakylene Glcol, a synthetic lubricant.

Generally speaking, coaches need about 1 ounce of PAG for each 7 feet of hose after the first 15 feet of hose. Roughly, a 40-foot coach will use about 92 feet of refrigerant (depending upon conversion, OTR A/C and a variety of other factors).

Take 15 feet off the measurement and you have 77 feet of line. Divide the 77 by 7 and you will find that you should have about 11 ounces of PAG from a fully evacuated system.

Taking the matter one step further, the 11 ounces will comprise about 18% of the entire capacity of the refrigerant system. This will create a total volume of about 61 ounces, or 3.8 pounds of R-134a.

R134a is a non-explosive, non-flammable and non-corrosive gas. There is hardly any odor to it and much heavier than ambient air. Yet, proper care and handling of 134a is required. At sea level, with mean atmospheric pressures and temperatures it will evaporate so quickly that it will freeze just about anything with which it comes into contact. The open container boiling point for 134a is -21.7F. This low boiling point makes it an excellent refrigerant. The tremendous heat transfer which occurs when a liquid boils forms the basic principle of an air conditioning system. The amount of heat required to raise or lower the temperature of one pound of water by 1F equals one BTU.

On a fully charged, enclosed system, the high side of the compressor can be as much as 200PSGI.

Yet, this is not a universal measurement, as ambient temperatures significant affect the temperature.

Here is just a sampling:

At 20F PSGI=18.43
30F=26.10
50F=45.48
70F=71.19
90F=104.40

Most experienced air conditioning mechanics do not measure the amount of 134a introduced into an evacuated system. Instead, they input air conditioning into the low side (Always the larger hose) at the compressor. They then slowly run the compressor, with an eye to the sight glass. Once the sight glass gets foamy and then stabilizes, they then consider the air conditioning system to be fully charged. This does away with the considerations of ambient air temperature and pressure regulation.

This is important for coach owners.

A quick measure to determine if an air conditioning system requires charging is to look at the sight glass while the air conditioning system is on (compressor running). If the sight glass appears to be 'foamy,' it is time to charge up the system with the requisite 134a and PAG, often sold in the same container.

Do not buy higher priced 134a refrigerant that has a 'leak stop' component, especially if you have OTR A/C. The Carrier compressor has very fragile reeds and seals on the inside and they can easily become clogged if PAG is introduced above the indicated levels.

[Joe Cannarozzi]

Jeff, we are a couple of steps closer to otr a/c. While nosing around inside the dash repairing the wiper squirters I noticed alot of oily resedue around the ducts below the evaporator so I pulled it and had it tested, its o/k. I then ordered the expansion valve that the evaporator threads into Im pretty sure this was the culpret because the hoses are good, either that or it was a loose fitting. Were going to vaccum it down again and if it holds vac this time. I am undecided if I will install the freon, have a local shop do it, or take it to a prevost charter co with a service garage that Im sure has done it a thousand times. Having spent almost 600 bucks for the R-12 I dont want any mistakes. Also I remember seeing somewhere you posted correct high and low pressure levels what were they again. One more thing, Jon also suggested I replace the compressor seal since the system is currently empty and could be a potential leak, it has also has arrived and needs to be installed. Lets get real specific like we know you can! Thanks.

[Just Plain Jeff]

That's a tough call to decide to change out the seal. It isn't a shade tree mechanic deal; there are some very specific procedures that must be performed when changing out a seal; for example: You can't handle a seal with your bare hands, it must be handled with air conditioning oil on your hands and the guts of a Carrier compressor are very finnicky.

Jon has been editing a story (since 2005) about the seal replacement, which was performed by an experienced air conditioning expert, which pretty much provides the entire procedure.

I guess it comes down to this: If you are at least a pretty good mechanic, or have access to an experienced AC person, I would go ahead and replace the main seal while you are at the stage you are.

One of the ways to check how your system is working is to put nitrogen to it at about 125lbs at least overnight and check it in the morning. If you have a leak, you'll know it for sure.

It's likely that Jon may run across this thread and we can move him to finish off the seal and recharging stories and Jim can get them posted.

Hope that this helps.

[Joe Cannarozzi]

Does anaybody know what the high side pressure should be for a cruise air?

[MangoMike]

Joe, When AAP installed my Cruise Air - this was the gauge readings.

http://mangomike.smugmug.com/photos/85665995-M.jpg

http://mangomike.smugmug.com/photos/85665994-M-0.jpg

Mike

[Jon Wehrenberg]

Those pressures are temperature dependent. Mike, do you remember what the outside temperatures were?

Joe, Lester taught the beer cool method at POG I. Add vapor at the suction side and as soon as you feel a distinct drop in temperature on the suction line with your hand it should be charged properly. (I'll bet the guys that make the Cruise Airs went by the gauges however.)

[MangoMike]

Jon,

Late May. As I recall it was about 70 degrees.

Mike

[dalej]

Joe take the top cover off there are about 15 1/4 hex headed screws. and then on the motor you will see two aluminum studs, pull out with a side cutters but don't damage them. add 5 drops of sewing maching, WD or a clear oil, no motor oil. If you haven't oiled the bearing for a few years then add 5 drops every 10 minutes for 40 minutes. four times. then add 5 drops per year. if you can see the motor thru a screen then you have sealed bearings and can ignore all that I have said.

[Jon Wehrenberg]

The bad news is that the only way to get the cover off is to pull the unit out. That is not as hard as it sounds because he just has to disconnect the three wires, two refrigerant lines and take out about 8 screws in the base, but he will have to replace the dryer and vaccum the system before recharging. I assume Joe means the small squirrel cage fan in the condensing unit.

[Joe Cannarozzi]

Got it, all three CruiseA/C on line for the first time since weve owned the bus! All the oil spots on the motors for the squirll cages for the condensers were assesable, some easier than others but I have done worse things, it wasnt too bad. Have made an appointment next Tues. for the OTR/AC. I continue to get conflicting advice about the compresser seal kit Ive purchased? The shop doing the work is a charter service with like 50 prevost and has been in buisness for 25+ years. Im thinking let them install it but what if I get there and they suggest dont do it? There are some dates on the compressor, looks like it was replaced 10yr ago or so. What if they put nitrogen in it overnight and it holds? What does the book allow for labor to put that seal kit in that compressor?

[Jon Wehrenberg]

Joe,

A tech familiar with the compressor can pull the heads, replace the valves and any other internal parts, and replace the seal in about 3 hours or less.

If you hold 300 psi of nitrogen overnight that system will not leak.

For R12 you are likely to have low side pressures of 38 and high side around 160 so if it holds nitrogen at 300 you are good to go.

Congrats on the Cruise Airs.

Jon

[Joe Cannarozzi]

Got a call from the shop forman at the garage were are using for our OTR A/C. He suggested that since we had the compresser apart to install the seal kit we should also replace the coil behind the clutch and also put two new bearings in. I told him to go ahead and the parts are comming. The bus will be spending its first weekend away from home since we got her. What the heck am I gonna do all weekend? Ill keep you all posted.;)

[Joe Cannarozzi]

Jon asked me to let everyone know what I am learning with my current repair. This is the first time I have needed any outside help with any repairs up to now. What Ive learned is that if there is even the slightest possibility that I think I can do the repair myself, Im fixing it myself. If I dont know, Ill learn how and then, FIX IT MYSELF! Shop has now had it for 11 days and counting.To make matters worse all the boose is in the bus. Ill keep ya posted.

[Jon Wehrenberg]

The pit and all my tools were the best investment I ever made.

My repairs and maintenance tasks take longer than the professionals, but I don't have the frustration of knowing someone is screwing me over and has their hands deep into my pockets.

Joe, FWIW, you can get a rebuilt compressor like ours for between $1200 and $2300 depending on who you get it from. Don't let the shop working on yours convince you their work is worth more.

[Joe Cannarozzi]

It ran it, blew cold air, but the compressor is overheating. As it turns out the connecting rod bearing is siezing up, compressor junk. If any consolation, they are crediting any related costs surronding it, parts and labor both. Also have replaced both expansion valves, the one for the main evaporator required removing the generator to access it. Had to be done, it was pluged with rust or something and wouldnt flow any freon. A new dryer was installed. One hose off the compressor was bad and 2 leeky fittings. What would I have done differently having the chance again? Taking into concideration this was a system that has been inop for who knows how long, I should of went ahead and had a rebuilt compressor right from the getgo. As it turns out we havent wasted any money but lots of time. Two weeks and counting. Im waiting on a call with a price. I know Jon posted what he thought it might be. My salesman thinks he might be able to get one also. Anybody else got one? A rebuilt compressor that is.

[Ray Davis]

Joe, I feel your pain in the A/C department. I had issues, and had my bus back to Prevost 3 times. In my cases my original compressor AND a brand new compressor both seized up in use, breaking alternator belts and causing no end of trouble.

In the long run it seems that the issue in my case was that R12 was put into this system where a previous owner had put in R114b (whatever that is), and the two did not mix at all, causing the freon to gum up, and cause the compressor to get hot and seize.

I've now got it back, still with R12 in the system, but I believe that they completely cleaned out the lines so that I *shouldn't* have problems again. I won't really say it's fixed until I've got 25-30 hours on that compressor. At the moment, it's blowing cold, but I've only got 6-7 hours on it. My last compressor (brand new) failed in about 6 hours on the road.

I would have replaced all the lines and possibly gone with 134 instead, but they indicated that would be about an $8000 repair bill. As it was, it came to over 1/2 that!

I feel your pain. My bus was in the shop for a total of 3-4 weeks time, causing me to miss a summer vacation trip. On the positive side, it's enabled me to take time off and go to POG2, and I'm really glad that is going to happen!!

Ray

[Joe Cannarozzi]

I have convinced myself we are making progress. All we gotta do now is find another and swap it out. I hope:rolleyes: Ours too is an R12 and Ray if you would like 30lb of R12, for reserve, I know I can get more, 577$. Im assuming it is going to continue to get harder to get and more expensive too. Once we slay this A/C dragon Ill get another for sure. This is not recycled stuff. Its new product, with a factory seal intact, from a fella Ive known for 15yr.

[Ray Davis]

Joe, that sounds like a deal. Are you going to be around at POG2? Perhaps we could connect there, and I could get a cannister.

[Joe Cannarozzi]

Ray, let me get this A/C repair behind, then Ill grab 2 more, 1 for you, and after I get it we will figure the rest. He had the sense to get 2 PALLETS of 30lb kegs before they pulled it off the market. Hes got a pallet and a half of them left, hes not advertising the stuff, so its there, its nothing pressing, and as soon as I secure it Ill let you know. Got a factory rebuilt compresser with a 1yr warranty, 1200$. It will be here tomorrow! Not planning to go to Santa-Fa, but that,ll be the last one we miss.

[Ray Davis]

Sounds good Joe. Hopefully I won't be needing anymore in the near future, but it might be a good thing to keep on hand! No hurry on my end.

[Joe Cannarozzi]

We picked up the bus Friday A/C repaired. Turned out didnt need a compressor at all. The machine they used to install the freon was miscalabrated and there was too much freon and it was returning to the compressor liquid and locking up. Next dragon, bushings and then awnings. They found there error when another A/C system devoloped the same symtoms for the same service with the same machine after doing ours!

[MangoMike]

See Joe,

Sometimes you do have good Karma.

MM

[Joe Cannarozzi]

Thank you oh wise one:) The bus thermostat has to be turned down or it gets too cold. This is good! The drivers air doesnt seem to do as well. Is this normal? Plenty of blower just doesnt seem to get real cold?

[Ray Davis]

Having just had my drivers air worked on, mine blows very cold now. One thing I learned a week ago, which confused me a bit. I had a little fogging going on driving home a week or two ago, so I turned the dash control to defrost, and turned the thermostat up to heat the air.

Later when I turned it back, I noticed that my dash A/C wasn't blowing very cold. Given that I'd just had it worked on, I'm still sensitive to whether or not it's functional.

Well, I guess it turns out that turning up the thermostat lets engine heated water into the core, to warm the air. I guess that makes sense. What I didn't realize, that when I turned it back to cold, it doesn't happen instantly, as it just stops putting hot water in the core, but that the hot water remains until the 190 degree water itself is cooled.

So, make sure your thermostat is all the way down. I thought my dash was broken again when this first happened!

ray

[Joe Cannarozzi]

These A/C compressors do not cycle on and off like you see in cars and trucks. When you turn the A/C on the compressor clutch kicks on and STAYS ON. The only way to regulate temp. when it starts to get cold enough is to introduce a little heat. If I had to guess I would say due to its massive size it would be too hard on the clutch for it to be kicking in and out all the time.

[Jerry Winchester]

Joe,

I would be curious to know if the recomended practice for turning the system on is to do it at idle and not running down the road? I make it a practice to not turn mine on above an idle, but I don't know if that is right. I just figured slamming it on from zero to 2000 rpm couldn't be good for it given the mass.

But that could just be because I have been hanging around Jon too long.....

[MangoMike]

Good quesion. I'm always flippin' mine off and on as we motor down the road. Especially hitting those big hills, off it goes for more HP. Dad it's too cold - off it goes in hopes of saving a little fuel.

Mike

[Joe Cannarozzi]

Jerry, Im just trying to apply a little mechanical common sence. I think what your doing is sensible. Mango, there is a thermostat to keep your dad happy and if you have a underpowered issue mabye you need an 8V hu! How fast ya need ta get up the hill anyway?

[Jon Wehrenberg]

I don't know if the clutch is adversely affected by turning it on when the RPMs are high, but my guess it is designed for that. On my old coach it did cycle so that is why I say that.

Joe, if you can use a mid or lower driver air fans speed. I think it is more efficient at cooling the air at lower speeds. Let us know for sure. I always use a mid to low speed on mine just because I hate the noise at higher speeds, and I think I noticed once that slower speeds are better at providing cold air.

[Joe Cannarozzi]

Our kitchen unit is having a problem with the fan speed. It has been there since day 1 and am just now getting to it. The problem is the the blower speed for the evaporator. It will run on full speed only and if we try to slow it down the blower will stall.

There are 2 possibilities I am concidering. First the capacitor for the blower motor or second the reostat at the control panel.

Custom or built in both do not even come close to describing how this unit is burried in the upper kitchen cabinats. Only after attempting multiple times to dimantel them sufficiantly enough to acess the blower I have finally gotten to the "evaporater unit" that contains the blower where the capacitor resides. Unfortunatly I once again had to stop and reassemble again because it looks as if I'm gonna have to unhook the feron lines and completly remove the unit in order to remove the top of it to access the blower and capacitor.

Has anyone had this trouble before or can confirm for me what component is bad before I go and open everything up again? What is stopping us from running the blower at slower speeds? I'm leaning towards the capacitor and would hate to find out its the reostat that would take litterally minutes to replace.

A few side notes.
First I've got the literature The converter put in the documents for the blower, its a Dayton and I'v got the part# for the capacitor, sweet hu!

Second I've discovered these blowers have oil points just like the blowers at the condensers. I'd hate to think that the converter expects owners to go to such great lengths on a yearly basis just to service them. On the other hand this one is 21 years old, never been oiled, and seems to sill be tight. There ARE oil points on these nontheless.

Third there is a fine wire screen across the front of all the evaporators to keep them clean and they plug up FAST. We have only had our bus for 1 season and I just rinsed it off for the third time and it was very dirty yet again.

[JIM CHALOUPKA]

Joe, Using your information about the situation I would changing the rheostat since in your words it is so easy to do. If that did not work only then look for something else. My perception of the capacitor is that it is for starting only, so once the motor is running you really don't need it, but it could be shorting out internally and cause a problen. Capacitors deteriorate with age. " Easy does it " first in this case. Don't tell him I said so I would deny it. See if Jeff B. needs a CDL driver. You and the wife could see the country in his converted race-car hauler semi-rig. You were retiring weren't you! http://www.prevostownersgroup.com/forum/ http://www.prevostownersgroup.com/forum/ JIM

[JIM CHALOUPKA]

Somebody already said when we don't know we will make it up.:cool: JIM

[Jon Wehrenberg]

You have to be licensed to lie. The certification test is tough.

[Joe Cannarozzi]

Jim I love you man. Read your responce and decided to check it by switching it with the reostat on the A/C mid-ship and WALA we've now got fan control speed. If yer ever in Chicago look us up we deffinatly owe you dinner :)

[Jon Wehrenberg]

Joe,

Park the Pete in April and come to POG III.

You need to teach a course on tricks of the trade and common sense, and bring guys like Jim to help.

Is there anything on the coach you haven't gotten into?

[Joe Cannarozzi]

Jon Yes absolutly. Lets go down the list.

I still have a box of radius rod bushings. I've only installed the steer axle.
I'm gonna put in a new alternater. Mind you this is all stuff I have already purchased but not yet installed. The fuel tank sending unit, this would be a great group project. Gotta pull the black tank. A windshield a side window and the drivers slider.

And as for projects we are going to do that arent already started or parts already purchased. A custom ceiling, currently all we have is a headliner and the mood lighting is O/K but the task lighting SUCKS. Were pulling the carpet for pergo and tile. I ,m pretty sure the toe-kick heaters are going for electric radient. I,m turning the E-spar into a boat ancor.

Here is what I think would be a great show and tell for a rally. Something I think we all can all use to some degree. Although we have no major body damage the front of the bus is TOTALY peppered with small rock dings and some medium ones as well. Harry you out there reading this? I would like to replace the 3 front stainless pannels. The flat one across the front and the two radiused corners. I think our bus would really look SWEET if we did that. It would look 10 years newer. I wonder, with a little help from our friends, if this is possible over the course of a rally? What do you think Harry is this something that could be done in 3 or 4 days or would we be going home with our toes showing:D

Thats some stuff off the top of my head, gimmi some time to think about it. If we ever showed up at a rally with my parts bin it would be all your worst nightmares:eek:

[Jon Wehrenberg]

Joe, I hope Harry jumps in here to correct me if I mis-speak, but I think you can deal with that front end for the cost of rivets (which are very expensive).

If you can get the panels off by drilling out the rivets, a flat heavy steel plate and some steel blocks and a hammer will take care of the dings by spanking them from the back side. Rather than striking the ding directly with the hammer, put a block between the ribs on the face side (down) and put a block over the ding on the rear and give the block a shot with the hammer. You don't want to make the ding worse by hitting it with the hammer because if the hammer hits at even the slightest angle you will end up with a dent on the face in the shape of the hammer.

The dings will then have to be sanded and blended working your way from 320 or maybe a little more coarse down to at least 1500 and maybe all the way down to 3600, followed by a buffing after you reinstall the skins.

Or you can save the large number of hours and just buy the ribbed panels.

[Joe Cannarozzi]

Yes Jon I was concidering that but lacking in KNOWLEDGE:rolleyes:

I followed the posts from santa-fa with great intrest!! I take it this rock dammage thing was part of the dissusion. This is good. Ya no JPJ mabye we need a club sec. to record minutes of rallies for the bennifit of those who can not attend.

Anybody second the motion?:eek:

I,m still uninformed as to how long it would take to do it? Harry, talk to me! I think there is about 65 rivets or somthing like that. Good rally project or no?

[Jon Wehrenberg]

Joe,

The rivets and removal time and cost are the same whether you bang out the dents or use new metal. The question is how much do the new panels cost and how much is your time worth.

Cmon, Harry. Jump in here.

[Joe Cannarozzi]

I called Elgin and priced those panels and was suprised I thought they would be more. Just under 800 bucks(they come unpollished) for all three tax included. Rivets 100 dollars for 100 rivets. I've also been informed by Debbie that some interior things might want to be replaced first. I hate when that happens.

[Joe Cannarozzi]

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.

[Gary & Peggy Stevens]

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.....!

[Ray Davis]

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 ....

[garyde]

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.

[Lee Bornstein]

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

[Jon Wehrenberg]

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

[Joe Cannarozzi]

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.

[Jon Wehrenberg]

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.

[JIM CHALOUPKA]

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

[Jon Wehrenberg]

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.

[matsprt]

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

[Jerry Winchester]

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.

[JIM CHALOUPKA]

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

[Just Plain Jeff]

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.

[Jon Wehrenberg]

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

[JIM CHALOUPKA]

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

[Joe Cannarozzi]

What a GREAT CLUB:)

[truk4u]

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:

[Just Plain Jeff]

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.

[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 ;)

[JIM CHALOUPKA]

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

[Orren Zook]

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 ;)

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?

[JIM CHALOUPKA]

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


The next time through stop in I am usually home. 2169784440

[Orren Zook]

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.

[Jon Wehrenberg]

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.

[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

[Joe Cannarozzi]

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.

[JIM CHALOUPKA]

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

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

[JIM CHALOUPKA]

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

[Just Plain Jeff]

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.

[mwalker422]

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

[Joe Cannarozzi]

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.

[dalej]

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.

[Jon Wehrenberg]

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?

[dalej]

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!

[Jon Wehrenberg]

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.

[gmcbuffalo]

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

[Jerry Winchester]

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.

[Jon Wehrenberg]

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.

[Just Plain Jeff]

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.

[Kevin Erion]

We left Zion this morning and are now at Lake Powell, Page Arizona. The temp is about 100 + or - a few. When I run down the road I use 2 cruise airs on the invertors and the dash air, no problem! When we are parked all 3 cruise airs are running with the temps set at 73, still no problem. I, like JDUB heve to keep the 3 girls and the wife cool, not an easy job but so far so cool.
Kevin