Project Jeep CJ-7
Onboard Air
York AC Compressor Conversion
INSTALLATION

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York AC Compressor Conversion

Testing the Compressor Clutch

The York clutch is just an electro-magnet and can be tested easily.  If you test it on the vehicle, do so with the engine not running.  Remove the belts to the York.  The pulley on the York should spin freely and easily.  If not, its seized and may need to be cleaned up or replaced. Apply 12 volts to the single wire coming off of the pulley clutch (the housing mounted to the engine provides the ground if the battery is in the vehicle).  The clutch should "engage" the pulley and no longer spin freely, rather turning the pulley should rotate the pistons with the York.  If you are bench testing the clutch, clamp the negative end of 12 volts to the housing and the positive end of 12 volts to the single clutch wire.  My clutch worked fine.  I still removed it and cleaned it up.  Don't paint the inside area of the clutch.  

Further York Identification Information can be found here.

York Maintenance Information

Mounting Options

On the Inlet side, I used:

• Tube-O fitting to 1/2" NPT (Kilby's Rotolock, part# 44760)
• Air Intake Filter (Kilby, Part# FS-07-050) 
• 1/2" NPT female to female, which apparently is also supplied by Kilby with the Air Intake Filter.  When I bought the filter, the this wasn't supplied.

• Tube-O fitting to 1/2" NPT (Kilby's Rotolock, part# 44760)
• 1/2" NPT female to female
• 1/2" NPT male to 1/4" barbed fitting (note: I might swap this out for a 1/2" NPT male to 3/8" barbed fitting and use 3/8 air lines instead.  This is  because the compressed air is moving so fast and the hose is small, the air heats up the hose, thus fatiguing it pre-maturely or blowing it off the 1/4" barbed fitting making a hell of a noise.)

The position I oriented the inlet and outlet in (picture to the right) seemed to be the best for clearance reasons and the direction I wanted the outlet hose to go. 

Next up was to assemble an array of NPT components.  As you can see in the picture to the right, the Air Manifold came in handy to attach all these components in a clean, organized manner.  When assembled into this unit, mounting them became easier since it was one solid piece rather than several smaller pieces.  These components were to accomplish the following things.  

• Remove oil and moisture from the compressed air using the oil / moisture trap.
• Stop the backflow of air into the compressor using a check valve.
• Regulate the power to the compressors electric clutch to control the air pressure using a Square D pressure switch.
• Attach a Relief Valve to open at a pre-set pressure to prevent damage or an explosive blowout due to pressure switch or clutch disengagement failure.
• Branch off air to several locations, to the front bumper (air tank), to the rear bumper (air tank), to the in cab air pressure gauge, and to my optional air horn.
• I also attached a 1/4" Coupler and an under the hood air pressure gauge.

When assembling these components as shown, I took note of how much space I had to work with in the area I was mounting these components.  My location of choice was hanging from the grill brace in my Jeep.  I test fit all the components first, checked the fit in its final location.  It fit good so I then used thread tape (the white stuff in small rolls) to seal every connection. 

With the array of NPT components assembled, it was time to mount them in the engine bay.  I didn't want to mount them to the fender for the reason that if I ever wanted to remove the fender to work on the engine, I wouldn't have to remove anything other than the fender.  Thus my fenders have very little attached to them for easy removal.

The best place I could find to mount the air array was to hang it from the grill brace that runs from the firewall to the grill on the passenger side.  This area was wide open and could accommodate the array of air components.

Creating the Hanging Brackets

Through a source of free scrap metal (dumpster at a metal shop) I acquired a few lengths of galvanized angled steel.  Using this steel I created some simple hangers that clamped down on the air manifold on one side and hose clamped to the oil / moisture trap on the other side.  See pictures.

Creating the hangers was simple.  To hang the Array from the grill brace I created two longer hangers and 2 short clamps using a the galvanized angled steel and drilling two holes at the top of the long pieces and two holes on the short pieces.  I then ran two 1/4" grade 8 bolts through the two halves of each brace to clamp down on the grill brace.  I had wrapped electrical tape around the grill brace so it could help prevent the clamp from spinning on the grill brace. (See pictures to the right).  

At the bottom of the rear hanger, I did the same thing with a short piece of the same angled steel and clamped it onto the air manifold.  At the front, I cut a slit on the angled hanger and ran a hose clamp through the slit and around the oil / moisture trap.

Overview after air horn install

York compressor outlet to Array

 I mounted the array of NPT components so that the inlet side was oriented towards the outlet side of the York compressor.  This allowed me to run a short line from the York to the inlet side of the oil / moisture trap.  Starting from the York outlet, the parts used to do this were: 

• Kilby's Rotolock (Outlet side)
• 1/2" NPT female to female
• 1/2" NPT male to 1/4" barbed fitting
• Stock air hose, cut ends
• Barbed 1/4" to 1/4" male port
• 1/4" female to 1/4" male elbow
• 1/4" female to 3/8" male adapter

To the Tanks
The air hose was an "off the shelf" stock 25' air hose with 1/4" NPT male fittings on either end.  I cut the 25' hose in half and used the stock fittings at the bumper ends.

When you look at the base of the blue air manifold, you'll see a 1/4" NPT "T" fitting with two barbed fittings facing in either direction.  These were for routing air to the front bumper and to the rear bumper.  

Where the hose entered the bumpers, I was going to locate quick disconnects so I could get a supply of compressed air at these locations.  So at the bumpers, I used 4 NPT components to "T" in three directions, to the Quick Disconnect, to the Bumper (air tank) and back to the air  manifold under the hood.  I had used a 1/4" NPT tap to tap threads into the 1/4" steel bumpers.  I located the inlet into the bumper air tank behind the bumper (facing the Jeep) so it was out of harms way.  The parts I used at the bumpers were: 

• 1/4" male to 1/4" female elbow
• 1/4" male quick disconnect
• 1/4" "T" with female fittings
• 1/4" male to male adapter (into the threaded bumper and "T")

The air lines were routed along the frame rail on the passenger side.

Air quick disconnect with "T" into the bumper. Same on rear bumper.

Air line to the rear bumper

Using 1/8" Nylon (or plastic) tube and 5/32 Press-To-Lock (or Press-in) fittings, a line was run from the air manifold, through the firewall and to an air gauge that was mounted under the dash board.  This was mainly so I could monitor air pressure from in the cab without opening the hood.

Electrical requirements for this onboard air system is minimal.  The only component that requires power is the York's clutch, which is basically just a magnet that engages the pulley to the York shaft.  The cutch has a single black wire that needs 12 volt to engage the clutch.

You don't want to supply power straight from a switch to the York.  That would require you to monitor the pressure and turn it off before you blow up your system.  Instead you want to leave that job up to a Pressure Switch.  Pressure Switches are common and can be bought from many suppliers.  Kilby Enterprises sells a Square D for $23.

The Square D pressure switch (49J59) is factory pre-set to cut-in at 135 
psi and cut-out at 175 psi.  You don't want to run pressures that high, mainly because of the stress it'll put on the York.   The cut-out pressure is adjustable so I adjusted my Square D to cut out at 120 PSI. The Square D has a 1/4" male NPT port.  For adjustment to the pressure switch, see the manufacturers instructions.  Along with adjusting the the pressure switch, you will want to adjust the pressure Relief valve to just above the cut-off pressure of the pressure switch. 

The Square D Pressure Switch has two Electrical circuits.  The circuits makes contact when the pressure drops below the lower air pressure limit, and disconnects when the air pressure reaches the upper limit.  For this application, you only need to use one of the two circuits.  Hookup to the York is a matter of running your 12 volt power line into the Square D pressure switch to one of the two circuits and then off of the same circuit run a power line out to York's clutch power line.

When you have air, you gotta get one of these.  I paid 8 bucks for it at a flea market.  Hooking it up was relatively easy after the air system was installed. Finding a place to put it was the hardest thing to do.  

I figured out the I could mount it right next to the array of NPT components under the hood and bolt it to the rear hanger.  I had to run a 1/4" air line (I used nylon air lines and Press-To-Lock)  to it since 1/8" didn't supply enough air for a good blast.  To control air flow, I used the push button part of an air gun and replace the inlet and outlet with threaded elbows.  I "temporarily" taped it to my steering column 2 years ago (I gotta clean that up).  

• Onboard Air Intro
    
• York Installation
    
• Bumper Air Tanks
    
• York Identification
    
• Hand Throttle