I don't know...but if 4 roof airs cause a Prevost to drive worse than having 4 Cruise Airs, I think I would "re think" my purchase of a Prevost. Roof airs are the LEAST of your worries of the "driveability" of a converted coach. So I guess I'm saying no, I don't agree. The only thing roof airs take away from a coach (in some peoples eyes) is aesthetics.
Senior Member
Donnie, can you further explain the installation procedure that produces a "quieter than Cruise Air" result? Do you know if this can be done on a Marathon with the a/c and heat pump combination? I am about to replace a unit so I am curious.Originally Posted by Donnie_M
Also, are you familiar with Marathons new very quiet roof airs, good bad or other wise?
Thanks,
Richard Beecher
2002 Marathon XLII 45
2010 Mini Cooper S
Senior Member
We try to avoid 95 plus temps. Our Royale has 3 roof airs, Prevost dash air plus a second Pro-air Royale installed that uses the dash air compressor also.Two summers back we did travel across I-70 across KS and MO on on to NC. Day time temps climbed to over 100. We stayed cool but found we could not get outside much when we parked for the night because of the heat. We made a promise to each other that we will stay away from hot places not because of the bus but because it was awful to us to try to see the sights. We stay cool here in the Colorado mountains during the summer.
Senior Member
Donnie,I can't disagree more about the weight on the roof changing the center of gravity of a coach,I am a pilot and anything loaded into an airplane has an effect,I am glad that you do not work for NASA with statements like that.The engineering school at the University of Central Florida would like for you to apply,their summer school starts next Monday,I think that you should start with physics 101.I have seen numerous post of roof airs failing and being replaced but not any on cruise airs failing,I am sure that they do but I think that roof airs keep many technicians in business,maybe that is why you are partial to an inferior product.
Jack, I appreciate your expertise as a pilot and value your opinion. My statement, "Roof airs are the LEAST of your worries of the "driveability" of a converted coach" comes from years of watching converters build coaches with the latest and greatest while trying to be the "fanciest" or "the most expensive" coach. Alot of people would be shocked if they were to weigh each tire position individually. I see no need for personal insults. I'm trying to answer questions with "factual" information. My ratio of Cruise Air to roof air repairs is 100 to 1! And more often than not the main problem with roof airs is poor installation, causing drain pans to crack and leak into the coach. A Dometic 15k roof top a/c unit weighs 100-115lbs, the entire unit. You are correct, I'm no rocket scientist, but please come up with a stronger argument against roof airs other than driveabilityb due to adding 400lbs spread out over the roof of a 40-45' vehicle weighing 54k. I find it hard to believe you have never heard of a Cruise Air failing, or the wonderful message that pops up on the SMX display "LO...P5" which actually means "LO..PS" for low pressure. Since it is a split system, you are relying on the "non rocket scientist" type to run the lines and make the proper connections. All the while preventing line damage from the constant movement of the vehicle and the need to make sure all lines are insulated properly. As I said..It's a no brainer...you can buy 4 roof airs for the cost of 1 Cruise Air. You can get the unit worked on any where you travel. Try finding a competant service center to work on your Cruis Air while traveling and then get back to me. Until the, have a good day!
To add to this, and I will quit!! My expectations of the acquisition of Cruise Air by Dometic Corp (you know that company that makes some of those EVIL roof airs that cause people to loose control of their Prevost while banking hard right or left...lol) have been disheartening at best! Dometic understands air flow and "theory", something Cruise Air never applied to their air cooled unit. I have been hoping Dometic engineers, some I know personally, would re-design the Cruise Air (air cooled) platform. They said in this economy "not a chance"! Also Dometic changed the warranty period, two years from the date of mfg, not the date it was put in service. Before Dometic bought Cruise Air, we could get evaporators, condensing units and whatever else we needed. Not now! Don't get me started on "inferior"!!!! Don't take my word for it call AAP tomorrow!
"I have seen numerous post of roof airs failing and being replaced but not any on cruise airs failing,I am sure that they do but I think that roof airs keep many technicians in business,maybe that is why you are partial to an inferior product."
Before you assume to know any thing about me, please take some time and do some research. I do not deal with INFERIOR...PERIOD!
The "perfect coach" would have five roof airs and Prevost installed OTR. Of course I am probably focusing more on a "H" series as that is the primary vehicle we see. An XLII would be "perfect" with 4 roof airs and Prevost OTR. The reason is, roof airs can be ducted as to eliminate the "hot spots" Jon was speaking of. Cruise Air efficiency drops with every 5 foot of ducting.
Roof airs can be made quieter by relocating the return air away from the unit and by mounting the unit on an "isolated" plate on the roof, which will also allow the unit to be removed and replaced with another one without having to touch the inside of the coach. I designed one of these systems a couple years ago and have never had a chance to actually do it. Certain people at certain company took my idea and tried something like it but totally effed it up. Right now my focus is trying to keep my Cruise Air customers cool since that is their only source of a/c while traveling.
Senior Member
I'm with Jack. I not only want to minimize weight, but I want that weight as low as possible. I don't know how much driving of coaches you have done Donnie, but up here in the area around the Smokies the roads wind and curve, and while you may not think so, sticking 400 pounds of roof airs on a coach as opposed to the weight of the Cruise Airs almost below the centerline of the axle will have a profound impact on an air bag suspension and how it controls the coach. That 400 pounds 12 feet above the road, and 10 feet above the air bags is a huge lever arm that forces the air bags (and the ride height valves) to have considerably higher internal pressures to resist leaning in a curve. Further, if the curves are spaced such that the coach ride height system gets behind the "curve" you have the leans counter to the way the coach would be expected to lean through the curve. The only difference is the frequency and spacing of the road curves will have a different effect on slow acting or fast acting ride height vales, but they will both be affected by that high mounted weight.
I'm a pilot also.
As to the assertion the Cruise airs are troublesome I have to disagree. Admittedly I don't have Cruise Airs Dometic has dumbed down to equal the quality of roof airs, but unless Dometic has completely redesigned them my 20 years experience with them has been very good. The biggest problem I see are technicians that do not clearly understand the operating pressure charts and as a result under or over charge the units. My first coach was 17 years old when I replaced all three condenser units, and I did that because one of the compressors locked up, and when I opened up the unit I saw how driving the coach for years in the snow belt during the winter had compromised the coils. I have four in the present coach which has a 14 year old chassis and so far I have not done a thing to them except clean the coiuld on occasion.
Senior Member
Donnie,We appreciate your experience and knowledge of Prevost and various conversions.I have had 3 coaches all with cruise airs and I have a Renegade Toter home for a tow truck,my experience has been that the roof air last 5 years on the toater home and the cruise airs do not fail(this is my experience).I see many post by others who have or are going to replace their roof airs at 5-8 years but not post of problems with cruise airs.You state that cruise airs fail 100-1 verses roof airs,why don't we see this on this site,maybe there is a problem with the installation in the type of coach that you are servicing.POG members might service their cruise airs better than the rest,I don't think so.If I were looking to purchase a new coach I would want OTR and 4 cruise airs,this has worked for me.
Senior Member
I've had both and for my part, I prefer the Cruisairs due to ease of maintenance and less noise than the roof airs. I would much rather stand on the terra firma and fix the cruiseairs instead of getting on the roof. Your worst nightmare is some bozo with work boots stomping around your roof, dropping tools and only putting half the screws back on the cover and then the leaks start to surface.
Oh by the way, I'm a Pilot also and 400 lbs on top of a 13' 4" bus would certainly have an effect on side to side stability in the extreme. In addition, I hate roof penetrations and there's nothing nicer than a clean uncluttered roof, not to mention less chances of water leaks.
I have never had any work done on the Cruisairs, whether busing or boating!
"why don't we see this on this site"
"I'm a Pilot"
"I'm a pilot also."
Jack, my neighbor has a 1971 Airstream with original roof a/c's so leave that 5 yr crap at the door!
Ya see, I said I was done with this thread, but I will add one more piece of info...I was involved in the design of the original "mister system" and the original "pressure equalization valve" (which now is incorporated in the programming of the SMX controls of the heat pump and opens the reversing valve 3 tenths of a second at start up to prevent cb tripping) that prevented circuit breaker tripping when the Cruise Air was "short cycled". The one thing I have noticed is the "pattern" here at POG. Basically..well...I will just leave it at that! This site has the wrong name! I think this site should be called LOG! I have not only seen this movie, I have the DVD and it is printed on the back of my work shirt!!! The attached is not to offend or to advertise, simply to make a point! Happy travels guys, if y'all wind up needing help, I'm a phone call away, and unlike others, I actually ANSWER my phone.
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