Low air light

[jatnip]

In my 1979 MCI 9 the low air light is starting to  cycle on and off and somtimes it stays on for a short time then after a while it does not come on for the rest of the trip.  The air guage show between 90#-to 120# the normal range of air pressure.  Questions.  Is somthing wearing out?  Where is this low light sensor located?
Thanks in advance,
Jim

[Beatenbo]

My light and buzzer don't go off til 90# and will come back on at 90# on my C3.

[JackConrad]

      I have a 102A3 at my place that I am converting for a couple near Chicago. That is about where the buzzer goes of on it.  I have never ran the air down enough to see where it kicks back on at.
     Not sure on your coach, but on our MC-8, there is a metal box about 4"X4" X3" that ids attached to the outside of the rear electrical panel on the side towards the engine/transmission. It is refered to in the manual as a Penn Switch. In additioin to activating the low air alram, it prevents the alternator from charging and the OEM bus AC from operating until you have air pressure. If you remove the cover, it is adjustable.  Since we had removed our OEM bus AC, when we replaced all the OEM wiring on our bus we did away with this box and installed a preset 65 PSI switch in the air line that used to feed this box. Hope this helps, Jack