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Noisy Dash Air
Just spent a great weekend in the bus for a shakedown and systems check. Great time and all systems go. The dash air blew pretty well, cooled pretty well and generally functioned in an acceptable manner. Only hitch is it creates a clacking noise that sounds like a plastic door of some sort opening and closing. It seemed to be more prevalent when accelerating and seems to come from under the dash in front of the driver. I haven’t gone in to investigate yet. Any similar experience or suggestions ?
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18 Replies
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could be a long shot but maybe you caught something in your front grill? Are your shutters open or closed?
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The question for XLII CC owners is did CC modify the dash air? If so is there anything unique to that causing the sound.
On my coach when I turn on the bus AC which includes dash air I hear the loud sounds of baffles or flaps moving and either opening or closing and then once they do their thing I just hear the fan. I would rather eat bees than try to work on the mess of wires and stuff behind and under the dash.
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I checked the grill as suggested and its all clear. Are any of the doors / flaps vaccum operated ? Many flaps, quacks or closing doors occur when accelerating and almost none cruising at highway speeds. My plan is to try and get some visual this weekend. The Prevost manual doesn’t have much as far as diagrams that help. If it’s a vaccum hose maybe it will be an easy fix.
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No vaccum hoses I know of….
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My previous coach was an 03 CC and on two different occasions thru carelessness – a ball point pen worked its way down the defroster vent and when the fan would hit it – well it was very noisy. Another ocassion was a business card. It is quite a job to get to the blower to remove crap that should never have been left on the dash.
Just ask Tom- he and Jim Keller removed the pen.
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It
wasn’t all that bad a job to remove the right portion of the dash.
The pen had fallen down into the squirrel cage and was driving Roger
nuts. -
Great suggestion!! Thanks to you both. That could easily be the problem. Plan to dive in this weekend and see what can be reached or at least seen.
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So my drivers a/c fan (OTR) started making a clackety sound like the squirrel cage was coming apart. Previously I had read that R&R on this fan was a real b****. I just read this post and have renewed hope! Can you actually get to something that has fallen through the defrost vents to remove it by going in through the dash?
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Doug,
My noise and your description sound very similar. My clatter was much worse on high fan than lower speed. Well I knew even less then and thought I had done everything short of a major disassembly of the front dash/wall to locate the problem. After spending significant weekend time trying to come up with a solution I was scheduled with Prevost Ft. Worth to get an annual done and mentioned the noise to the Tech asking for ideas. He didn’t have a suggestion but when I picked the coach up, no noise. I checked my invoice, found no charge or explaination and called back for details. I never got enough detail to find out what exactly was done or how it was accessed but was told it only required some screws to be tightened so no charge. It had never been a requested item to be addressed by Prevost so nothing apppeared on the invoice. I am sure the dash/wall was not disassembled so I have always assumed it was reached under the dash around the steering area or from the bumper compartment. This is a long story and probably not very helpful except to say it may be an easier fix than you think. Hopefully someone who really knows the design of the system will have an idea from this information. -
George,
Thanks for responding. I didn’t know if anyone would remember your 3 year old post! I will try to access it from the top. Others have said it may be easier to remove the stainless from the front of the bus to get to the blower! I’m up for trying something easier first.Doug
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Doug,
I think you have to go through the dash. I helped Roger years ago, don’t remember the vintage he had,
but we found a pen in the squirrel cage that had fallen in from the defrost vent. -
So Truk
What does it mean in your signature, 73208. I know your coach is #732, but what does “08” mean😀 -
The last few years our dash fan has made a screeching sound especially at high rpm more so than low rpm, and more so in colder ambient than warmer. So I called Prevost parts and they said most likely the center hole in the fan had worn on the motor shaft, allowing the fan enough play to rub on its squirrel cage. So for twenty five bucks, I ordered a new fan wheel. We were scheduled to visit Prevost Quebec this past June anyway, so I let them put it in. They said there are actually two fans under the dash, one is under the instrument cluster and is very difficult to access. The other is in front of the passenger behind the stairway handrail. So they swapped the one that was easier to access on the right. They went in by loosening the trim piece that the handrail is mounted to. The top of the dash was not disturbed. So that fixed it for us.
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When it first happened I went in through the panel at the top of the stairwell. Two fans but are for heat – pass side. The drivers air blower is located somewhere behind the dash or below the floor. I will take the dash apart before I try to access below the floor (and maybe below the slide!). I think Joe Camper had experience with this. 1999 prevost chassis w/ OTR.
Thanks anyone with suggestions.
Doug -
I would highly recommend putting a screen between the vent face plate and the hose leading to it.
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