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Maintenance bulletin Mi97-24 Prevost Question
Is there a way to perform this test without disconnecting the power source and using a supplemental power supply? Can a basic/adequate positive presure be developed with the Over the road evaporator blowers and maybe just open the condensor side so there is no negative pressure being developed from that part of the system? If so, could you describe that procedure and pitfalls.
Would such a test also help to identify/locate infiltration points into the basement bays?
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5 Replies
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The test procedure for finding water leaks by pressurizing the vehicle can be done if you have the full a/c system. You just need to open the Evaporator door (driver’s side of the vehicle) and the system will presurize just fine. If you only have the dash a/c, then you would need to construct the type device we do with blower motors and a hose with a piece to fit into the toll window. Then you are able to pressurize the vehicle and spray suspected places on the exterior for air excaping. Remember that there will be area that will leak air and that is perfectly normal (window edges, etc.).
This test will not help with luggage bay leaks as we do not heat or cool tghe bays. For these you need to check door seals and proper closure of the doors to be properly sealed (H3 VIP especially). Some bay leaks can be coming from above via the side panels. But this should show itself with the pressure test.
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What do you mean by normal leaks ” window edges”? I have been fighting window leaks for years and still can’t time the source. They are really ruining the panels below the windows. Only on the awning windows? Any ideas on this? I have resealed all the rubber around the windows both glass and buss side with your silkaflex black tube.
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Thank you.
If I use the full A/C system and open the evaporator door, how do I set the fresh/recycle air switch, open or closed?
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You want to set the damper so it is wide open to bring in outside air (At the main evaporator), and close the dash air damper so it recirculates so it is not exhausting air unless you run the dash air, in which case open that ro outside air and run the fan full speed so even more air is brought in. Then the coach will get the maximum inside pressure for leak detection.
Make sure the sink drains are plugged and water is in them. It doesn’t take much negative pressure such as we get while driving to drain them opening a path to outside. Don’t forget the dryer vent, or the Fantastic fans.
Or you could move this forum inside your coach. There is a lot of hot air here…….
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“Or you could move this forum inside your coach. There is a lot of hot air here…….”
I think you are in the wrong forum, wouldn’t a discussion of the “blast-o-gas fuel cell” be more appropriate in the Electrical forum?
……………. and thanks.
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