The best reason to have an onboard air compressor: air up your tires when you get off the trail. Another (and more important reason) is to engage the ARBs. Some other not so obvious reasons - trail fixes (reseat the bead), air tools, be everyone's friend.

When I decided I wanted to install an on-board air system on my TJ there weren't a lot of options. I could go with an off-the-shelf electric compressor, or I could figure out some sort of system for an engine driven unit. Well....I didn't want electric. So I had to find a way to mount a York air-conditioning compressor (an air-conditioner off AMC and some other 1970's engines).

At the time I was researching and building my system, no one had put a York compressor in a TJ. The problem is that the engine compartment is a lot smaller than on previous Jeeps. The fenders sit closer to the block - extra clearance in the wheel wells and taller shock towers. I spoke with Harold at Therold Industries about my options before he retired. He said he hadn't sold any kits to TJ owners for installing a York. Apparently, no one was interested in removing its stock air box (I already had in favor of a Turbo City Rock-It tube and K&N air filter) or cutting the fender for clearance. I didn't fear the Saws-all, so I ordered a kit. Good thing I did too - it was the second to last one. His kit was good for Jeeps with or without AC - something a lot of people worry about, but I didn't. The good news is even though Therold Industries is no longer, the kits (including the hard to find pulleys) are now available from Brad Kilby. Send him a note if you're interested in putting on board air in your truck - he's got adapters for all sorts of applications.

Before you go off into the junk yards to grab a compressor, head over to Obi-Wan's page and read up on what to look for. The York came in a few different varieties over the years and in various engines.

Installing a compressor is very straightforward. Trim the fender out of the way (mmmm....power tools...), bolt the supplied compressor bracket onto the engine, change the pulley on the alternator and bolt it all up. Run a wire to a switch in the cab. All told, it took about 2 hours to do.

Installing the filters, manifolds, tank, pressure switch, hose and all that other stuff was a challenge. In spite of all the room in the TJ's engine compartment, there is very little usable space because of how curved everything is. I decided to mount the manifolds and all that on the ABS shelf below the master cylinder (ABS is yet another option I didn't get and don't miss). I tried about 50 different combinations of connectors before I found a pattern that would fit. Included on the shelf:

• Intake from compressor
• Check valve
• Pressure switch
• Regulator (ARB)
• Mini water filter
• ARB solenoid for rear (and room for front - later)
• 2 lines out - one to tank and one to front of vehicle
• Check out the schematic.

I borrowed a trick from Steve Friend and put an oil coalescing filter first thing off the compressor (well, not first thing - found a 4' section of 5000psi hose to cool the air). I mounted the filter above the area in the firewall that the A/C lines would enter the cabin (next to the battery) Then, again following Steve's advice, I installed an oil return hose from the bottom of the filter (with a valve) back to the intake on the compressor. So while the compressor does blow oil, I get all of it (or most of it) back again before every trip - I just open the valve and turn on the compressor. Sucks the oil back in to the compressor. When it's done, I turn off the compressor and close the valve. Wala! The York has oil in it again.

To increase the storage capacity of the system, and to allow the consistent use of air tools, I installed 2.5 gallon tank from Sun Performance. My intended mounting location was over, and perpendicular to, the rear pinion. Didn't work - the TJ's parking brake is in the way.

I decided to mount the tank parallel to the muffler and on the driver's side. Because of the body lift, the bottom of the tank sits even with the bottom of the frame rail (the picture is taken from a lower angle). I also added a 125psi popoff valve to the tank as another safety in the system.

Soon after I removed my transfer case drop, I discovered the compressor was hitting on the top of the shock tower under acceleration. The reason? The engine tilted forward a bit when I raised the transmission.

I decided to go ahead with a 1" body lift and the Currie 1" lifted poly motor mounts. The motor mounts gave me plenty of clearance under the compressor, and the body lift made running the lines that much easier - helped clear the 35's too.

I had been contemplating the lifts anyway, so this wasn't really a hardship - more of an opportunity.

If I didn't want to deal with all the headaches I went through, I would use a Nippendenso or Sanden compressor - they are essentially the stock air conditioner and use the stock brackets and belts. However, I like the power of the York. I know that the others put out a lot of air too, but...well...you see...York compressors are cool.

A month after I finished the project, I found blue hose that almost perfectly matches the Jeep. Sure would look better than the orange! Same rating too.

Tomken makes a parking brake lowering bracket for use with their lift. I think it would drop the lines enough to be out of the way of the tank. It's quite possible I could have put the tank where I wanted to.

• 1/4" inline filter - Grainger #6B290 $11.58
• 3/8" coalescing filter - Grainger #6B262 $47.60
• Filter bracket - Grainger #6B244 $5.89

With everything I did, total cost was about $550 plus a lot of left over fittings. I figured "What the hell? I'm going to need them for something anyway..." Well, they're still in a box somewhere awaiting some friend's project.