Replacing and source for Nason pressure switch air parking brake

[ok-rver]

Bob Nodine has a very good, detailed method to replace the Nason pressure switch with a reliable spst, (on/off), switch and relay. When mine started acting up a week ago, I came very close to using his method but I did not feel I had the time to get it working. REV wanted $140 plus shipping for the switch. Airline Hydraulics had the part for under $45 with $22 shipping (ouch, no free Prime). Received part in 3 days.

A brief discussion of how I replaced mine in a 2004 HR Scepter. About 8 screws around the perimeter of my side console plastic filler plate with the air switch, Allison pad and other switches. Two of the three screws the cup holder were holding the plate down. There is a trim ring on the cup holder that pops off and gives access to the screw. The plate would only come up an inch or so. Pulled the 5 or so screws holding the side console to the wall of the motorhome. It turns out the Nason connector was the short wire. Once it was disconnected, the console tilted away from the wall. Remove the air switch knob and lock nut, unscrewed the very long bolts that held the valve to the plate and the valve was accessible. Unscrewed the pressure switch (very tight) and screwed in the new one with thread lube. bolted back together and everything worked correctly. Less than an hour of time.

New switch is slightly different than the old. Failure mode was as Bob and others have discussed. . The NC contact with out air showed open. Now that I have a failed switch, I will cut off the wiring harness and maybe pick up the parts needed to make up Bob's system. Or if this one lasts the 18 years the first one did, I will never replace it.

[JDCrow]

I’ll have to find Bobs thread as this is new and Greek at the same time. Thanks for a new system to learn and project to add to the mental file 

[ok-rver]

Articles/Technical papers/ a closer look...  will get you to his PDF that has all of the post combined.