Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

box in air step

September 09, 2012, 03:18:48 pm

Guys this may be normal but we have not used our 99 u320 in while and when i started it today i heard what i thought was a air leak so i traced it to a box in the cavity by the air step..It is about the size of a 3 by 5 card with one air hose going in the top...when that line is moved the air sound changes...when i switch the engine off, it stops completely and i hear no leak..is this cause for concern?

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Re: box in air step

Reply #1 – September 09, 2012, 03:27:35 pm

 It means you have to trade it in for a new coach !!!I have just gone thru a similar thing as was hearing a rap rap and air sound from the "Box' I took mine out and apart and found that the air line to the top nipple was not sitting securely so just wrapped some teflon tape around then put the plastic line back on and a ty-wrap  around and no more noises or air loss. I think it is just age-normal.
John H

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Re: box in air step

Reply #2 – September 09, 2012, 07:03:21 pm

Have fun with the new coach

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Re: box in air step

Reply #3 – September 09, 2012, 10:48:53 pm

Dave, It sounds like that is the vacuum generator.  If so, it should have an air line going in to it from an air regulator behind the steps and a vacuum line going from it to a round can that is a vacuum reservoir.  There should also be two wires to provide 12V when the ignition is on.  If the air or vacuum line is loose, it should be an easy fix.  On mine, the entire box was rusted out and I replaced it with a 12V vacuum pump from FT and simply removed the air line and plugged the connector for it at the regulator.

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Re: box in air step

Reply #4 – September 10, 2012, 05:50:38 am

Dave, just did the the overhaul on mine. The box is the vac generator for the dash ac controlls. The bottom of my box fell apart, put a new aluminum bottom on it, the problem with it was the vacuum storage canister (fruit juice can was leaking), you can get a new plastic one from about any auto parts store. You also need to make sure all of the vacuum lines are good, as a vacuum leak anywhere from the step to the ac controls will cause the pump to to run all the time.

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