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Onboard Air Setup #1
After scrounging for air after every run I finally decided it was time to install an air system of some sort. I wasn't happy with the capacity of the electric compressors (I even hated borrowing air from people with them) and decided an automotive air condditioner compressor was the only way to go.

The only disadvantage to having on-board air is all the new friends you aquire at the end of a run. Suddenly your popularity quotient increases dramatically.

Selecting a Compressor

I considered a York piston compressor with it's seperate oil reservoir, but couldn't find one with the serpentine pulley. They are also larger and don't really offer any benefits over the rotaries (see footnote). I found a stock Sankyo rotary compressor from a Jeep and decided that it could easily replace the existing idler pulley. This compressor was off the shelf in a Kansas junk yard so it didn't come with any mounting brackets. The factory mounting brackets require the use of a different belt for the A/C setup. Since I carry a spare serpentine belt and didn't want to replace two relatively expensive belts I made brackets that use the non-A/C belts.

Before you lay out the cash for the compressor connect a battery and make certain the electro-magnetic clutch works. While the clutch is engaged spin the compressor and see if you can feel suction and/or pressure through the ports.

Mounting the Compressor
Sorry, I didn't take any pictures of the brackets, but they are just two pieces of angle iron 1.5 x 2 x 8 inches long. The hardest part was getting the compressor with a 5 inch pully to replace a 4 inch idler and maintain the same belt tension.

Building the Manifold
The main reason for choosing this particular pressure switch was because it has four 1/4" NPT ports and becomes a compact manifold that all the other parts screw into. This switch will start the compressor when the pressure is less than 90 PSI and turn it off at 125 PSI by cycling the magnetic clutch on the A/C compressor.
The parts in the list below came from Grainger equipment and supplies.

Addendum: For some reason (heat, vibration or oil) the polycarbonate bowl has cracked on three different oil separators. I have since discarded them and am looking for a small industrial grade oil separator.
I also replaced the inline check valve with a more positive check valve triggered by the pressure switch instead of the input/output pressure bias. The picture doesn't quite match up to the components now.

Grainger Parts
Other Misc. Parts
Item PSI Stock # Price   1/4" NPT Brass Street Elbow
Pressure Switch 90-125 5A537 22.93 1/4" NPT 2" Brass Nipple
Safety Valve 150 5A709 5.90 Compressor to Manifold Hose
Unloader/Check Valve 150 5X780 9.10 Manifold to Bumper/Tank Hose
Mini Air Line Filter 150 2Z766 15.55 K&N Air Cleaner
Pressure Gauge 0-160 1X754 4.10 Air Cleaner Adapter

Mounting the Manifold
I mounted the manifold to the bulkhead that supports the radiator. There is a rectangular hole behind the headlight with a lip that has to be ground down to 1/8th inch. I used 1/8th inch thick washers behind the angle iron mounting bracket to clear the lip.
The air hose comes out of the bottom of the manifold and goes under the grill to the front bumper.

The source of power for the compressor clutch is a wire from the fuse block that is controlled by the ignition switch. If switched power is not used the battery will be drained if the air pressure drops below the pressure switch setting. I've also included a master switch so the compressor can be disabled when not in use. The switch could be mounted under the hood with the manifold, but I chose the dash so the air tank(s) can be filled as I approach the end of a trail.

Grainger also sells Dynaquip quick connects that will accept any of the three different style connectors available (automotive, industrial and ARO 210) for air lines and tools. This way I can use hoses and accessories from anyone I'm traveling with. Part numbers are Dynaquip DW-340, Grainger 6CX02.

I found that 7/8" crutch tips available from the local hardware store are a perfect fit for the quick connect couplers on the air lines. This way you don't have to dig mud and debris out before each use.

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