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Bus Air Inspection
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I have the same display Mike has mentioned on my coach. Right down from it is a knob that I believe Liberty installed to control the fan speed for the “passenger” area. Be carefull and make sure your shades are up as it will make them bubble out and look like your dog was behind them.
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My bus is a 1999 chassis and has the two rheostats for fan speed like Dick, temp control knobs with no temperature numbers. No digital. Have to carve it in stone.
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Jerry and Gayle asked me what the low side gauge pressure should read?
It varies with ambient conditions, and if the compressor is unloading cylinders, but generally speaking 40/190 are acceptable pressure #s.
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I also have the knob for passenger fan speed on my 2000 shell, but have digital temp. Control. The knob does nothing! Can only control driver speed.
i have noted that a lot of air is directed through the defroster vents when it is running. I have the vent setting on and still get a lot of air towards the windshield. Anyone else get this or is a diverter not working? When I hit the buttons for defroster and heat I hear them open and close but can never get just the vents to blow only.
Hitting the recirc button decreases outside air and seems to make driver area cooler.
Mine freezes the wife out on passenger side seat, while I am comfy in the captains seat.Patrick Collins ….I have coach #467. Built right after yours!
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All, this is the digital unit I have – expect most have. The fan is for the driver area only , and that is also how the Prevost manual reads. I just thought it odd not to have a fan speed available on the passanger side, sounds like some do….I have certainly not found one on my 99′ shell / h3sorry , the pic doesn’t show the digital readout as this was a picture I took a while back.
william, mine also seems to always have a lot of defroster vent air pressure and noise when running regardless of setting. I use the recirculating mode when I need heat and make sure my front air vents are closed (mine are normally open when driving) -
William,
I had a 2001 Libert XLII and had the same problem, all the cold air went out the defrost and the dash adjustable vents were a joke. One guy a ran across laid bean bags on the defroster vents to force more air out the dash vents. I could not ever find a solution in talking to Liberty or Prevost. I think you’ll find most have the same problem with that vintage.
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on a side note,
how nice it is to have a commercial bus chassis.
Just today I found out one of my customers runs a over the road truck shop specializing in refrigeration systems. They also maintain several fleets of seated coaches, and provide primarily AC service for those buses. When I spoke to him and mention what system I have on my bus he immediately said to just bring it over and eat throw the gauges on it and do a double check to make sure everything was in spec no big deal.
such a difference from a traditional class a scenario where there are few people that know how to work on things, and they typically are too busy to be able to get to it… When they want to get to ithappy travels
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William, the way you are describing your system is just like ours. No matter the setting, there is always air that comes out the defrost vents and like Tom said the dash vents dont really do a whole lot compared to a passenger vehicle. However, when the system is on and the fan speed is turned up, it has always kept me comfortable while driving. The bigger problem I have is the noise I have to listen to for the first 5 minutes of a trip before warm/cold air starts passing through the vents. My 4 year old son dropped a Lego through the vent and you can hear it in the fan. Good thing it goes away after a while.
Im going to double check on my knob that Liberty installed to see if it really does anything. Why would they put that in there if there is no way to change the passenger fan speed?
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I’m on my 3rd H, 2 2001’s and now an ’04. All of them have had the same problem with not being able to cut off the defrost vents while on A/C. The ’04 I have now is better than the others, but still the air comes out the defrost at all times.
On one of my ’01’s, I finally put black duct tape over the defrost vents, and the dash vents worked great then, in the summer time, when I didn’t need any defrost.
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Our A/C system looks very much like Coachcrazy’s above if not exaclty (Driver air left side, AUX air right side)
We, too, get a lot of air out of the defrost vents compared to the dash air vents. The AUX air that works behind the seats has vents that I can set to blow on me (driver’s side) that keeps me nice and cool.
I also set a store-brought fan on the steps blowing directly at me. I like constant air movement and ‘C’ does not. I would probably have to cover the front defrost vents if it wasn’t for the AUX air picking up the slack. I know that we probably lose a lot of coolness as those windshields are so big and not double-paned. The air blowing out of the defrost vents is probably not a bad idea.
On edit: I forgot to mention that we have a function on the digital read-out in the Prevost message center. I can toggle through it and it gives me the high and low pressure of the dash air system. When it’s off, those two numbers are equal.
Mark
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Patrick wrote: “Im going to double check on my knob that Liberty installed to see if it really does anything. Why would they put that in there if there is no way to change the passenger fan speed?”
Is the fan for the coach OTR on high? medium? or low? Maybe there is a wire loose somewhere. Could be as simple as the ground or hot wire at the rheostat.
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On our bus it’s my understanding that Prevost designed the defroster system so that they can never be completely turned off. Don’t ask me why?
I noticed this shortly after we bought the bus, so I had these defrost vents custom made by a friend.(see pic)There is a flap inside that allow them to blow at the windshield or the passenger. NO! he is NOT interested in making anymore. Sorry.
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If there is not sufficient air flow or heat on the windshields in cold temps such as experienced in the north it is difficult if not impossible to keep the windshield clear. The problem gets worse as the amount of glass increases such as on H models and rthe XLII.
There should be a way to regulate the air flow, but if there is its effectiveness is minimal.
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I sure like those customer made vents. Do you know if he adapted something else? or are they completely scratch built?
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Mine has the 2 fan speed knobs one for driver and one for coach. And 2 tempature Rheostat knobs for the same. No need to re-direct any air when it is working properly. Usually have to turn drivers fan down to keep from freezing. My OTR blower sounds like a jet engine. I think it is louder than the generator. Like someone else said, I raise my blinds in coach a few inches to keep the blinds from puffing out.
Note : Turn off OTR A/C when You drive into a gravel / Dusty parking lot, Unless You want to create a dust storm.
Safe travels…….
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