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junair mp75 of332

Aux Compressor Replacement
This is yet another thread on the subject of replacing your auxiliary air compressor.  I didn't find all the answers I was looking for in the existing threads so I am adding this one.   Please see other threads in this forum with titles:
110 compressor
120v air compressor replacement

I think I replaced the original Jun-Air Model 6 that had been running faithfully for untold hours since 1999.  Mine was mounted with the generator.  This provided a location within the sound absorbing structure of the genny enclosure.  Between my lousy hearing and the very quiet JunAir I never heard a thing!  I had to install an hour meter in the front right side bay with the pressure switch just to monitor its operation.  I would check the meter and if it only slowed a few minutes a day, I knew all was well.

Then, the hours took a huge jump and I knew the free ride was over.  A quick check of the exit pressure on the JunAir confirmed its demise.  Due to my remote location for the winter I chose not to tear it apart and try a repair.  Besides, it had served me well and deserved retirement.

I was a little shocked when I started looking for a replacement.  Turns out JunAirs are expensive.  There was discussion here about going with an inexpensive Chinese compressor going by the model number MP75 and sold very reasonably by California Air Tools.  My emails and PM's to a member who had planned to do that conversion went unanswered, so I was left wondering what happened.
Tom always finds these fantastic eBay deals and had found a JunAir for cheap that way.
In the end I bought a new JunAir OF332 delivered to by door for the grand total of $412.28.   While not a McCloud deal, I think I did alright.

Jun-Air has an internet presence and I was able to find manuals and schematics online, but nothing exactly for the OF332.  Another member had mentioned confusion on how to connect this model.  I received the compressor with one side of a 9 pin connector.  It contained 8 wires coming from the compressor.  After digging through the documentation and ringing out the wires here is what you need to know.  The black and white wires just go directly to the hour meter.  I had no use for that meter, so removed it and the wiring.  Of the remaining wires, you just need to know the correct three of interest - Hot, Neutral, and Ground.  Connect as follows:   Hot to Brown, Neutral to Blue, and Ground to Green/Yellow.  Remember, almost nothing you can do with 120vac is going to hurt a 220/120V motor.
The compressor has two stages - clearly marked low and high.  I had to do the plumbing.   Output of low to input of high.  Be careful with your purchase and use of fittings.  Some threads are not tapered and require fittings with "o" rings to seal.  The press on tube type appears to be for 10mm OD, so had to order that.

I have attached some pics of the completed installation.  This is an oil-less rocking piston pump rated for continuous use.  I fully expect it to last as long a I have the coach.

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Russ White
1999 45' Double Slide - Factory upgrade 2004
russ that is exactly what i did.

the one i bought was "used" but had zero hours on it. it was in a mount with an hour meter and was set up to be two separate compressors. i plumbed the two stages together. only thing i did different was i went to a parker store and had them make me a high temp hose going between the two stages.

mine is in the genny blower bay so noisier but still not bad.

i shock mounted it and it helped quite a bit.

2002 45'8" Newell Coach 608  Series 60 DDEC4/Allison World 6 Speed HD4000MH

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