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On Board Air Install for Jeep TJ











  The following is from my good friend and neighbor, Jeff.  He posted this on our local BB and I think it is a great “how to” on doing an inexpensive OBA set up on your TJ with AC:


  "Here is roughly what you will need (may vary depending on how you decide to set it up) you should be able to do this under $70 including tank.  You will loose your AC. 


  This was done on a 2000 TJ your application may be different.


  Before I get into this, please ensure that the components you choose are rated for over the max pressures and temperatures that you will use. Compressed air even at 150 or less psi can be very dangerous and cause serious injury or death. I take no responsibility for what you do. This is for informational purposes only.


  3/8th air line:  I used high temperatures 300psi max pressure line form Home depot. You can get it by the ft at Home Depot length will depend on how you choose to set your system up and if you run a tank or not.  I used a total of about 8 ft for my setup.


  Filter/ moisture separator:  This is important it will separate the oil from the compressed air and allows you to keep the compressor oiled. I recommend that you get one that has a valve at the bottom of the separator to evacuate the oil back to the compressor. I used a Husky 417-548 from Home Depot around $20.


  Tank and or a manifold:  Tanks can be had for around $20 or so and the manifolds can go from a simple 3 port screw on type you can get at Lowe’s or Home Depot for around $5-$8. If the tank only has one port, you will need to add a manifold.


  Pressure switch:  This is needed to engage the compressor clutch when the pressure drops to low and then disengages the clutch when the upper set pressure is reached.  I got mine from 4 Wheel Supply Cole @ 800 606 6421 It is a QuickAir part #PS001 and allows compressor on at 80 psi and off at 115psi.


  Most important is the pressure relief valve/pop off.  This will ensure that the system does not over-pressure and will open and allow excess pressure to be released in the event that the pressure switch or compressor fail to operate correctly.  At Lowe’s or Home Depot around $8 and are set to open around 120 psi.


  Intake filter:  I used a breather filter from Autozone for $9.


  You will also need various fittings and smaller line to allow oil return to the compressor intake.


  I then got started and bled off the pressure from the AC system (you may need to have this done by a shop if you feel unsafe, they can also evacuate the system as well) the larger line is the intake (low pressure side) and the smaller line is the output (high pressure side). 


The Conversion:  Paragraph numbers = picture numbers:


1.    Unbolted the input line to the condenser (located at the lower passenger side of the radiator. You now have the compressed air side free.


2.    Next cut the intake side using a pipe cutter. (look where the filter is) You can place the intake wherever you prefer (some put the intake inside the cab). I left it there


3.      For the oil return I used some line and fittings from the  local ACE hardware store. I drilled and tapped the aluminum line and then inserted the fitting I used a good coating of epoxy to ensure no leaks. I used compressed air to blow out the particles and then flushed it with alcohol to ensure no contaminants were left in the line after the drilling and tapping.

  a.    I also installed the filter at this point

  b.    The intake side is now done at this point, so we'll move on to the compressed side


4.    The next issue was to connect the pressure side to the 3/8 air line I would use for the rest of the system. I removed the pressure side for the drier located on the firewall.


5.    This left a connector end that I decided to use a die and cut some threads in it. I then coated it very well with epoxy and installed a 3/8 NPT adapter to it.


6.    Connect the airline from the adapter to the air filter/separator. The airline then goes to the tank, which is in the back of the jeep so I ran the line through the firewall then to the tank.


7.    In the picture, you see how I hooked up the drain to go to the intake that was mentioned earlier. With the system under pressure open the small valve at the bottom and the oil is forced back into the intake to keep the compressor lubed. I wheeled hard the following weekend, changed a bead lock tire using an impact wrench and only about an ounce or two of compressor oil was blown into the bowl. A quick turn of the valve and the oil was back in the compressor.


8.    To finish the pneumatic side of this project the air line was attached to the tank, on the tank is an auxiliary valve to allow filling the system from an alternate source such as C02 or another compressor this was done in the event that the system fails, It would allow me to still use lockers.


9.    Picture of the manifold and gauge on the dash.


10.  Basic wiring so the below diagram is for pneumatic and electrical.  


  One charge of the 3-pound tank to 110psi allows me to operate my ARBs well over 50 times before the pressure drops to below 80 psi.  On the tank is the pressure switch, a drain, and the over pressure release. From the tank, I have a line going to the manifold. The manifold has four pressure regulators One for each ARB, one for the system pressure gauge located on my dash (normally wide open to monitor system pressure) This one can also be used if one of the other regulators fail. The final regulator is for accessories (tire inflator, Air tools, etc). If for some reason the ARB solenoid fails, I can also operate them manually from the manifold by bypassing the solenoid.


  Time:  About 3 hours if you have all the parts assembled.


  Cost:  About $70 or less if you can find some parts in your garage.



  If the engine is running at about 1900 rpms you get near C02 tank performance for airing tires and running air tools."

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