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  • Bed lift

    Posted by Mike/Lisa on September 22, 2017 at 9:08 am

    MAC valve associated with bed lift pneumatics leaking so got new one and went to replace. Unlike others I have replaced in various places around the bus, this one has a 6A4 diode connecting both sides of the 12v supply. See pic. I am not smart enough to figure out what is going on. Haven’t seen that on any of the other MAC valves I have replaced. Can somebody educate me? Thanks. Mike

    Pic is mislabeled. Diode is 6A4, not 6AW. Sorry Mike

    Andy replied 9 years, 1 month ago 5 Members · 5 Replies
  • 5 Replies
  • Andy

    Member
    September 22, 2017 at 10:33 am

    Suppression diode for the inductor (coil) in the solenoid. You’ll want to keep it, unless you can verify that the new solenoid has one built in.

    https://en.wikipedia.org/wiki/Flyback_diode

  • Archived

    Member
    September 22, 2017 at 11:11 am

    Makes sense (I think). Now the question in my feeble mind is why the others I changed out (exact same item number) didn’t also have that? They were all on the air operated doors. Would there be something about the bed lift that would indicate the use of the diode in that application. Thx. Mike

  • Archived

    Member
    September 22, 2017 at 3:07 pm

    That’s a good question. I imagine the switching hardware to activate the solenoids is similar in each application? Maybe if one was controlled by a crestron or something like that, and the others by a switch, that could explain it?

    Either way, I think I’d keep it the way it is.

  • Tim

    Member
    September 22, 2017 at 3:33 pm

    Mike,

    On my coach, I have an SMC valve that controls my airlines to/from the regulator.

    There are muliple areas where my bed could leak, and instead of replacing everything, I disconnected the airlines and use the struts already there. I did reposition the struts for an easier lift. My wife can use one hand. I go under my bed maybe once a month and for me, it was not worth finding/fixing all the leaks in the bed.

    In fact, many newer coaches don’t even use the airbed system anymore.

  • Gerald

    Member
    September 22, 2017 at 4:54 pm

    Tim, couldn’t agree more and, in fact, have put a shut off valve in line (are you listening Jon?) as I put things back together. Took the advice of B and left diode in circuit. If any more trouble, will shut off the air to the bed totally with that valve and use those struts. The whole thing seems over engineered – but so do many other things on these coaches. I am a KISS person. Thanks to all for commenting. Appreciate the input. Mike

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