[Fred]

exactly what one is otr air ?

[Roger]

OTR Air is the Prevost system air conditioning unit located mid ship. Not all converters leave it installed opting for roof air instead. But I was in 110 degree heat in NM last year and it was 72 degrees inside, ya gotta love OTR air!

[Fred]

Just rub it in!

[JIM]

Yeah, Ours in this 91 will freeze you to death. On midship blower no adjustment full blast. Just shut vents on drivers side and turn blower down in front. Sure nice in these 100 degree days we had this summer on way to the beach on the Gulf coast.

[Archived]

is it the one with compressor on right in engin compartment?

[glen]

Yes. The compressor is a Carrier six cylinder compressor and the output of the least efficient Prevost OTR heat and AC system is about the same output as that of six roof or Cruise Air units.

[Dale]

Yeah, they is a control on drivers panel to mix heat to raise temp on ac system but I would just as soon wear a sweater. Walked outside when we hit the Gulf coast and thought I went blind. My glasses fog over last weekend. Wife griping all the time. Heaven!

[Archived]

And cruise air is the unit under bus like a central a/c system ? (runs on elect)

[Brian]

Right again. Cruise Airs (remote basement mounted condensing units and upstairs mounted evaporator units) are house AC units that run from 120 volt house power, and are akin to roof airs.

[Archived]

So Jon in your opinon what is the one to have i have cruise air it wont get the bus down to about 74 in fl in summer and it is draging a&& to do that, i use to have a wanderlodge that had 3 roof airs it would freez you out but it was noisy.I wish i had otr for traveling without generator , my dash air keeps my belly cool but dose not help my back.

[Gerald]

I have had three coaches with Cruise Airs. Their output is approximately the same as roof airs with most all the individual coach AC units being 13,000 with some at 15,000 BTU.

So their performance should be comparable, assuming they are properly charged and the condensers are clean. The test of that is the temperature difference between the supply and return air temps, which is likely to range between 15 and 21 degrees. When mine have been out of that range it has usually required a tweaking of the freon charge and if it is just right it is as high as 21 degrees spread.

Our coaches have had more cooling capability that we needed except when it has been exceptionally hot. But on 90 degree days we are in the low seventies in the coach with two Cruise Airs running. Cruise Airs are not good for cooling when driving because the air for the condensing unit is the hot air radiating from the highway. Roof airs are up top getting cooler air and work well for driving. Cruise Airs are fine when parked because they are picking up the cooler air from the ground in the shade of the coach. They don’t work so well if the bus is lowered and the parking spot is deep grass that affects air flow.

My objection to roof airs is the noise. The coaches we have been in that use roof airs have been universally noisy, some so much so that the noise level is annoying. That is likely poor installation however.

As to planning on one AC keeping the coach cool, our experience has been that we need two, and that is for air distribution more so than capacity. One will keep the front cool or the rear cool but not both due to the aisle preventing good air flow throughout.

[Russ]

My coach is a 1988 Angola Conversion and the way the Cruise Airs were
installed left much to be desired. The front one had an extremely small
fan on the evaporator and moved very little air, plus the cold air
outlet was just above the return which resulted in very little cool air
distribution. I reversed and increased the air flow by installing
the largest squirrel cage type fan from Granger that I could fit behind the
evaporator, I insulated the fan housing with high density foam to
prevent sweating since I was now moving cold air through it, then I
routed that air through insulated ducts to air registers that I placed on
the far left and right of my front over head console. It made a
tremendous differece in the cooling ability. The rear air required a similar
modification. The center system was the only one installed as the manual
suggested. Place the intake low to the floor and the outlet high in the
coach, it blew really cold air but not much air flow. I dissembled the
cabinet that the air ran behind and discovered the fan was the correct size
but the cavity the cool air ran through was not insulated and had many
leaks which was allowing the cold air to recirculate directly back into
the return or just lost behing the cabinets. After those problems were corrected it’s now my best system,
I think that’s because the vents are located correctly. We stay in Florida at
campground where most of the sites have 30 amp service if I have a
little shade, that 1 center Cruse Air keeps our bus comfortable, I mean
about 75, if it’s not over the low 90’s outside.

My other
problem with the Cruise Air installation are the intake and outlet locations
for the outside condenser units. In it’s current configuration the
inlets are behind the front bumper or on the side of the coach and the
outlets are underneath. That’s probably best for driving but not good
for being parked because the hot air that exhausts under the bus, rises
up and at least some of that hot air goes back into the inlets which
need all the cool air they can get. I don’t know, maybe I’ll install fans
that reverse when I’m parked.

Anyway, I just wanted to share some of my experiences.

Ken

[Bob]

One mistake I just made was to ignore the installation of units and how the quality of the installation has a tremendous impact on performance. Ken is correct in pointing out how valuable a proper installation with good separation between supply and return air flows is in determining the performance of any AC unit. One thing also unmentioned is the filters for the house AC units, roof or Cruise Airs need to be part of normal maintenance. Over the years several owners have had evaporator coils choked off as a result of lack of filter maintenance. The same goes for condenser coil maintenance.

[Russ]

Jon,

Very Good info ! ADD AC FILTERS TO THE LIST !!!

Thanks,

Rocky

[Archived]

As long as we are morphing into AC system maintenance there are a couple of other things to be aware of.

If the coach has OTR pull the filters and clean them also. One of the biggest impediments to OTR performance is a set of dirty filters. Their placement seems to make them get dirty very fast. They are usually behind a removeable small panel in the 3rd bay back over the evaporator, but some conversions have located them in other places.

Because most owners do not get under their coaches it is easy to overlook the Cruise Air baffles that have to be in place to separate the cool intake air from the hot exhaust air from the condensing units. In some cases the baffles are not only a directional exhaust baffle, but a crosswise baffle in the center of the coach to provide a dam to block recirculation of hot exhaust air. The baffles beneath the coach can become crushed or lost.