Onboard Air

York AC Compressor

Conversion

Its a well known fact in the offroad community that an aired down tire will have better traction offroad than a fully inflated tire. It's common practice by those who know this to air down their tires into the teens or even the single digits just before hitting the trail so they might get the best traction possible and to smooth out those teeth rattling bumps. Airing down is easy. You just let the air out. The problem is getting air back into the tires after your day is done because if you're like most people, you have to drive your rig home and proper air pressure is critical for safe highway driving.
There are several ways to get the air back into your tires.
Air Options

• Hit a gas station on your way home and pay 50 cent for about 3 minutes of use, then proceed to dump a few bucks. That is if you can even find a station let along one that has an air pump these days.

• Carry one of those mini compressors that power off your cigarette lighter port. They works but the piston is so small in these units that airing up a 35" mud terrain to 30 PSI is like waiting for paint to dry. For years this was my method in my other 4x4s. Besides the time it takes to pump up, the compressor always got hot and I'd always wonder if it was going to make it. But it was better than nothing.

• Carry some sort of pre-filled onboard air tank that you'll pre-fill before the trip and empty into your tires after wheeling. Just make sure you have enough reserve to fill all your tires. These can be anything from a tank of compressed air from your own compressor to a compressed C0? high pressure tank. Whatever option you used, it will eventually run out and probably at the moment you need it most.

• Higher quality electric compressors can be purchased which can be mounted inside your rig. People who have ARB's air lockers will typically have a compressor for the air lockers. These are better than the typical mini electric compressors with a higher CFM but most of them will still take almost 10 minutes to air up a single tire and will cost at least $250 after all is complete.

• Convert an engine mounted AC compressor to pump air rather than the Freon and mount an auxiliary tank somewhere on the vehicle. The most common compressor to convert is the York compressor (currently owned by Climate Control Inc. "York" was the previous manufacturer). The York doesn't rely of the Freon to oil the system because it has its own oil reservoir making it idea for this type of conversion. This article deals with assembling an air system around a York compressor.

Here are some advantages to using this type of air system:
o Cost - If you search junk yards, ebay, used parts dealers, these compressors can typically be found for less than 50 bucks. The most common vehicle the larges York is found on is Volvos manufactured from
o Available Parts - You can obtain parts to convert the AC compressor's fittings to NPT fittings, which allows you to use common, inexpressive NPT air system components.
o CFM - The larger compressors have a high CFM allowing you to pump up your tires in a matter of minutes.
o Power - Since these compressors are engine mounted and drive off your engines crank, they are powerful and will pump air just as efficiently at higher pressures while bringing your reserve tank up to the max pressure.
o Reliability - The AC compressors are built to last, at least as long as the vehicle is in service. As an air compressor, they will continue to provide years of service as long as they are properly maintained.
o Versatility - With an auxiliary tank, you'll have enough air reserve run air tools and the larger York compressors will actually keep up with the CFM demand of most air tools. You might even use your air reserve for other things like a backup to your ARB compressor or an old air horn off of a Kenworth 18 wheeler, etc.
o The Cool Mod Factor - With a complete onboard air system in your rig, you can chalk up a few point for a cool modification that almost ranks up with the onboard welding system. You'll not only fill your tires quickly but also help out your wheeling friends air theirs up too as you show off your onboard air system.
Planning the York Conversion
While building up my 1978 Jeep CJ-7 I decided to take advantage of the 210 York AC compressor I acquired on the AMC 360 and convert it to pump air. As it turned out I had the largest of the York compressors, the model 210, which was a big plus. I also had the advantage of having all the factory brackets that bolted the York to my engine so I didn't have to figure out how to mount it. I understand that most people will be looking for a compressor and brackets to mount their compressor to their engine. To help with the search for compressors and mounting options please see the York Identification page and the Installation page for more info on other applications.
For this project my focus was on a few things. First I had to convert the pump's Freon fittings to air fittings. At first I was searching through the bins at my local Ace Hardware store, looking for the right threaded fittings to convert what I had to an NPT barbed air hose fitting. I was getting close to finding what I needed to adapt the freon fitting to NPT but not quite. Then a friend in the know told me about Kilby Enterprises and their selection of specific parts to make the job easier. So I took into account what I had and drew up a parts list of what I needed to convert my York to an air compressor and place an order.
Parts List - Acquiring the parts
The first thing I had to do was determine what the system would look like and what parts were necessary to successfully pump air, regulate the pressure, route the air lines through the vehicle and store the air. I had enough foresight while building my bumpers to create bumpers that doubled as air tanks so storing the air was a done deal. To read more about the custom bumpers / tire rack project, click here.
Pumping the air (converting the York), routing and regulating the pressure was what I had to figure out. I looked at a few diagrams I found online to learn that that system needed a few key components. Air entering the York had to first be clean so an intake filter is required. Air exiting the York pump had to be cleared of oil that comes from the York using a Coalescing Filter, better known as an oil / moisture trap. Note: Apparently the amount of oil can be reduced with modification. I'll explain that later.
Next in line, a check valve to stop air leaking back into the York. From there you're on the pressure side of stored air. I used an air manifold to branch out to other components, which I could clamp down and mount some where. Here you'll regulate the pressure with a pressure switch, which will provide or not provide power to your pumps magnetic clutch depending on the pressure in your system. (power to the pressure switch will first go through a fuse block, then a power switch to turn it off when not in use). Beyond that its accessories like the tank, gauges, lines to outlets, a relief valve, etc. Below is a breakdown of what I had and needed including a diagram of my system.
Components I had:
• York AC Compressor - I had acquired the York 210 series when I bought my engine. The 210 compressor is a 2 cylinder, 10.3 cu. in. displacement with 4 CFM at 90 psi while running at 1200 rpm. See the York Identification page for more info.

• Mounting Brackets - Needed to mount the York compressor to the engine. Not a problem for me, I had the factory brackets already on my AMC 360. If you have an AMC 304, 360 or 401, look around for the factory brackets. AMC used the York in their Full Size Jeeps (Wagoneers, Grand Cherokees, J Trucks). If you have another engine, check out Kilby Enterprises. If still no luck you may have to fabricate something.

• Air Tanks - When I designed my custom bumper project, it included creating a front and rear bumper that doubled as air tanks with a combined volume of 2.5 gallons. Auxiliary air tanks can be purchased in a variety of sizes. Kilby Enterprises sells a few low profile tanks that can be mounted in an inconspicuous place on your vehicle.

• Air Manifold - While an air manifold may not be necessary, it does help branch off air lines and components. They are cheap, can be found almost anywhere NPT fittings are sold and help keep the layout clean and organized under the hood. I used mine to not only organize the components but also made up some simple clamps that hung it from my grill brace on the passenger side. More on that on the installation page.

• Oil / moisture trap (Coalescing Filter) - A necessity with the York. This will capture the oil that will blow out the outlet valve.

• Pressure Gauges - Its nice to know what your current pressure is. I chose to mount two air gauges, one under the hood and one in the cab.

• NPT Fittings - Various easy to find NPT / Pneumatic connectors and fittings. In my system I used mostly 1/4" NPT parts. These include elbows, T's, couplers, reducers, male to male or female to female connectors where necessary, 1/4" and 3/8" barbed hose fittings to NPT 1/4" and 3/8" fittings (male and female). Again see the diagram, which will explain a lot. What I didn't have I picked up at a local hardware store.

• About a 25 foot length of 1/4" pneumatic air hose to connect the front and rear tank (bumpers) to the air manifold. The hose had male NPT ends. I cut the hose in halves and routed each half to the front and rear bumper.
Components I needed:
• Tube-O fitting to 1/2" NPT - These are used to convert the York's inlet and outlet to the standard 1/2" NPT air fittings. (Kilby's Rotolock fittings)

• Square D pressure Switch (or various other name brands) - A necessity to automatically disengage the York pump from your crank when the desired air pressure is reached.

• Intake Filter - You don't want to suck dust, dirt and mud into your compressor.
• Adjustable Relief Valve - Just in case the pressure in your system reaches beyond the maximum desired pressure for whatever reason (pressure switch failure, York clutch seizure), the relief valve will blow, allowing air to escape (and make a hell of a noise to let you know).

• Check Valve - When your York is not pumping air into the air system, you need to prevent the air from seeping backwards into the compressor. Check Valve will do just that.

1 York AC Compressor (factory installed on an AMC 360 out of a Jeep Grand Cherokee)
2 Tube-O fitting to 1/2" NPT (Kilby's Rotolock fittings, )
3 1/2" NPT female to female (kilby or a hardware store)
4 Air Intake Filter (Kilby Air Intake Filter, FS-07-050)
5 Square D pressure switch (set to 120 psi off) (Kilby, 49J59)
6 Air Manifold (hardware store)
7 Adjustable Relief Valve (set to blow at about 130 psi) (kilby, NC25)
8 Pressure Gauges (on at manifold, one on dash) (hardware store)
9 Oil / moisture trap (Coalescing Filter)
10 Check Valve (Kilby, CB38)
11 1/4" T, 3 female ports (hardware store)
12 1/4" Couplers, male port (hardware store)
13 Barbed 1/4" to 1/4" male port (hardware store)
14 1/2" NPT male to 1/4" barbed hose fitting (hardware store)
15 1/4" male to 3/8" (the Oil / moisture trap is actually a 3/8" so the fitting on both sides of the moisture trap is a 1/4" male to 3/8" male. (hardware store)
16 1/4" Elbow, male one side, female other side. (hardware store)
17 Male to Male connector (hardware store)
18 1/4" Elbow, male one side, female other side. (hardware store)
19 1/4" NPT to 3/8" Nylon Quick Connect (Grainger) NOTE: The air horn and pressure gauges use different sizes, pressure gauges use 1/8" Nylon Quick Connect and Air horn fitting use 3/8" Nylon Quick Connect.
20 1/4" male NPT to 1/8" female NPT (hardware store)
21 3/8" Nylon Quick Connect to 1/8" male NPT (air horn adaptor) (hardware store)
22 Yard Sale acquisition - Really loud air horn off a '76 Mack
23 1/8" nylon air hose (hardware store)
24 Stock 1/4" air line with male factory fittings (hardware store)
25 Air Tanks, Custom Front and Rear Bumper Project26 1/4" NPT male to male (hardware store)
27 Air Blow Gun — 1/4" female Inlet, 1/4" threaded outlet.
28 3/8" nylon air hose for air horn (needed volume) (hardware store)