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Slide Vacuum switch
I am hoping to canvas the forum for an issue we are having with our slide. Last weekend we tried to retract our slide and all that would happen was the tag air would exhaust for 30 seconds and then the switch indicator light would flash twice while continuing to hold switch open. Indicating the inflatable slide seal was not deflating. We ensured that we were in travel mode on the suspension and that our aux. air was at full pressure. I was able to speak with Troy at Liberty and after reviewing the various components I noted to Troy that the Vacuum Switch led was not illuminated on the slide controller. Troy suggested that we bypass the vacuum switch once all the air was exhausted during the retract cycle, we did and the slide retracted as normal. I ordered a new slide vacuum switch from Prevost and installed it, we continue to have the same problem after the installation trying now to extend the slide (same error code). As I watched the slide seal pressure regulator during the cycle attempt I did notice that pressure was not releived on the gauge as I believe it should, i think it should actually be on vacuum at the tail end of the cycle, witch should trigger the vacuum switch. Has anyone had similar experiences that could guide to the next step? Thank you!
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5 Replies
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Prevost on line has the manual for the slide out. It sounds like the vacuum pump is not working,if you remove air manually it functions correct?
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I believe there is a 90 degree knob up high in the drivers side OTR bay on the rear bulkhead that dumps air in the seals. Have you tried to manually turn that knob to see if the seal deflation will allow the slide to cycle in and out until you get the problem resolved?
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Thanks Jon, I found the relieving shut off valve upstream of the pressure regulator/gauge which allowed me to deflate the slide seal. I continue to need to jump wires across the Vacuum switch in order for the cycle to continue and open the slide. I reveiwed the wiring and pneumatic diagrams with the valve arrangements and I believe that Jeff is correct in that my Vacuum generator is not working properly. When I monitor the cycle, I removed the vacuum line to the valve bank and had slight pressure not vacuum in the line during the cycle, there was air venting from the generator but likely not sufficient to create a vacuum through the venturi of the generator. I think I understand the reasoning behind having sufficient aux pressure during the slide operation, it would seem to me this is the likely reason to facilitate the operation of the Vacuum Generator. The Vacuum switch was probably fine and did not function because it was not reading a vacuum, therefore did not complete the circuit to the logical control to advance the subsequent steps in the slide cycle. My next steps I believe will be to remove the vacuum generator and check that it is not blocked, also I will check the air pressure at the outlet of the vacuum valve. Hopefully I’m on the right track.
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Since Prevost had several versions of slides and controls for slides they will have to be the ones for you to discuss this issue with, but on mine if I deflate the seals, trip the 5 or six breakers, I can manually run the slides in or out using the pendant located in the evaporator bay.
Do not take that as advice because yours may be different and you also must retract the pins at the valve otherwise you risk punching a hole in the slide glass with a pin. The point I am making however is there is a procedure and Prevost can tell you specifically what it is for your coach.
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Just an update, I confirmed that our problem was the Vacuum Generator, all is working good now. When I first looked online for parts from Prevost, it was quoting September delivery and a cost of approximately 3500, I found a local distributor of SMC equipment and placed the order, the only issue was it was not a stock item and had to come out of Japan, the cost was 300, so I ordered two and paid to have it couriered. I may never have the issue again, but for 300 it’s kind of handy to have.
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