This article is about the installation of an on-board air system to air up tires. This project adds a second A/C compressor. This compressor is a York compressor found in many vehicles, from sedans to trucks (incl. semis). The original Sanden A/C compressor is left in its original location.

Considering the amount of custom work in and around this project, this article is best suited as a source for ideas, rather than a step-by-step guide.

The A/C is fully functional and inspite of some minor A/C hose modifications is completely OEM. The York compressor is mounted in a custom-made bracket and is in-line with the serpentine belt, albeit a slightly longer one.

In other words, there is no additional V-belt cluttering up the engine bay, and no need to build a bracket that allows to tighten such and additional belt!
> However, mounting the York compressor into the existing serpentine belt configuration required a new 6-groove clutch. This clutch is readily available through commercial truck part vendors, but also adds (~US$100!) to the overal cost of the project (CJ Jeepers are probably quite familiar with this setup).

The York is mounted on the right side of the engine, mounted in an approx. 45 degree angle.

Please be aware that this setup requires some modifications of the eninge bay layout (depending on year/model, this may vary considerably from what is shown in this article).

• Battery needs to be moved elsewhere
  I used a Diesel XJ battery tray to move the battery from the right side to the left side of the engine.
• Possible interference with A/C lines. Should not be an issue if properly put into consideration ahead of time.
• In the case of the battery relocation, a custom air intake (such as a K&N cone filter) needs to be installed (since the big air intake box has to make room for the relocated battery).

This on-board system already provided outstanding results. In fact, the first time out on the trails with it, I managed to slice open not one tire, but two. In conjuction with the TyrePliers and this on-board air system, tire repairs were almost fun, if it weren't for so many! I.e. many good folks now expect you to fix their tires. "Come on... just this one more tire... good practice for ya'..." Sure! My back was a constant reminder of that for many days after that.

• A: The home-brew air intake.
• B: The Diesel XJ battery tray.

• Heavy fabrication ahead!
• ALWAYS wear eye protection!

• York A/C compressor*

The best source of information regarding York (aka. CCI, Tecumseh) compressors can be found directly at the source: Climate Control (CCI)

http://www.ccicompressor.com

Don't forget to print out their excellent work shop manual!

http://www.ccicompressor.com/SrvcManl.htm

A printed copy of this manual will prove invaluable during the search stage. Bring a copy along while hunting for a good compressor on your local salvalge yards.

• A: The coil.
• B: The original double V-belt clutch.
• C: The original Volvo mounting bracket.
  Although promising to be useful at first, it turned out to be of no use later on.
• D: The York compressor.

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• 6-groove clutch* for York compressor
  Part number: 02-0804 (6-groove, 5.8" diameter, 1 wire)

*The clutch shown in this picture is already painted to match the rest of the engine bay's paint scheme. New they are black.
Good source for these: Truck Air Parts!

http://www.truckair.com
Call these friendly folks for a local retailer near you. They have outlets covering all of North America (esp. along busy Interstate routes, it seems.)
(800) 338-6626
info@truckair.com

This is also the ideal source for information regarding any A/C related items (York, Sanden, whatever). Excellent PDF files with pictures and diagrams, etc.

Some Steel:

• 5" wide, approx. 1' long, and approx. 1/4" thick steel.
• Misc. bits and pieces of steel

Misc. small items. such as:

• Approx. 1' of copper tubing for the pressure switch relief
• Air hose (I used 1/2" and 3/8" I.D.)
• Air hose coil (to reach the tires)
• OEM hoses (black, far right, --I painted the ends yellow) from Volvo-York
• Engine bay shelf (second row, left).
  This used to be the shelf for the pressure overflow bottle of the non-HO I6.
• Pressure switch (85psi on, 125psi off), such as Grainger 5A020
• Check valve (i.e. "one-way valve") with 1/8" NPT unloader connection, such as Grainger 5X780
• ASME safety valve (150psi), such as Grainger 5A709
  If the pressure switch should fail to shut off the compressor, the safety valve will open once the system reached 150psi to avoid serious damage.
• Some type of air tank.
  I used my rocker panels as storage tanks. Both combined provide close to 5gal volume, which isn't much but does help a lot.
• Hose barbs
  I used 1/2" hoses from each rock rail tank, but used 3/8" air hoses after they joined for higher air flow rates.
• Many 1/4" Tees, extensions, elbows, nipples, connectors, etc.
  These 'misc. small items' can add up to quite a bill. I paid close to a US$100 for just these little parts.
• Air intake filter
  I used this chrome-and-yellow valve cover breather that I found in the 'rice isle' of my local AutoZone store.
• Hose clamps suitable for the chosen size air hose.

Most items listed here can be found in local hardware stores. However, the pressure switch, check valve, and safety valve are most likely a specialty item not found at the local corner hardware store. Check either: Grainger or McMaster-Carr and other similar industrial suppliers.

• A longer serpentine belt

I ended up with this "6 1066" belt. This is most likely not exactly what your particular project may require. Every custom project will require a slightly different length. The belt is therefore the last item to be acquired for this type of custom project. More on this below.

• Welding equipment
• Metal fabrication tool (grinder, cutter, chop saw, etc.)
• A/C clutch removal tool (home-made will work)
• Well equipped do-it-yourselver tool collection

The Quest for the Perfect Belt:

Even though the belt issue is the last to be addressed during this type of project, the belt (re)routing is crucial for the understanding of the goal of this project.
Shown here is the '87-'90/'91 XJ/MJ 4.0L non-HO serpentine belt routing. Somehow, the additional York compressor must be squeezed in here...
This belt is a "6 1025" belt (OEM Jeep I6, '87 to '90). These aren't true part numbers, but part numbers can be derived from these numbers. I.e. the "6" refers to the number of grooves in the belt (and therefore its top width of 27/32"). The three or four digit number, here "1025" refers to the length of the belt, in inches. However, it is not as straight forward as it may look. It could be 102.5", but it doesn't necessarily have to be that length! (It is actually 103".) Therefore, double-check before ordering.

• Cut your old belt if it is no longer of use.
• Install is as if it were a regular belt.
• With the adjuster, i.e. power steering pulley in the lowest position, take a measurement.
• Same as above, but the pulley in its highest position.
• Calculate the middle using above measurements.
• With the pulley in the middle, take a third measurement. Does it match your calculated measurement?
• If yes, go ahead and get your serpentine belt. If not, but the measurements are two very close together, go for the shorter one. The belt will stretch and it is better to have a bit of extra reserve in the pulley travel rather than to max it out and end up with a sloppy belt.
• To find out what lengths are available and which vehicles they are designed for do the following:
• Go to NAPA Online (or similar).
• For example, enter a Gates compliant number such as "K060949" in the "Non-NAPA Part No." field and hit the "go" button.
• Since it is an invalid number you will be presented with a comment to that effect.
• Increment the Gates compliant number by one, i.e. "K060950"
• You will be seeing a link to click for more information, such as width and length, but NOT which vehicle it is for.
• To find out which vehicle this belt is for, go to: Gates Automotive Catalogs page and load the Light Truck catalog, which is a 342 page PDF file.
• Look through all the listings, page by page, year by year, vehicle by vehicle, and see if you can't find a match to the particular belt in question. Some belts are very common such as the K06100, but others can be extremely rare such as the K060994, only found in one year of Chevrolet van and one model year of Ford vans! Careful, you don't want to end up with such an exotic item if you can avoid it!

Since this very cumbersome, I already went through some of the above mentioned steps and collected this information presented in the table below. A true time-saver for our MADXJ web visitors!
If any of our readers can offer data to fill in the gaps in the table's third column, please submit such data. Thank you.

Here is a table with serpentine belts that I found. It may not be complete, but it is a good start. Obviously, I only list those belts that are roughly in the neighborhood lengthwise for this project.

The First Belt Routing:

Shown here is a diagram of a first alternate routing attempt. I eliminated the idler pulley and 'streamlined' the routing somewhat similar to my '97 4.0L Jeep Cherokee. It didn't work too well. Moisture, even in form of humidity, allowed the belt to slip. Many of the images below show this routing. It worked most of the time, but I didn't feel comfortable with this configuration and switched back to a 'near-OEM' routing of the belt. This first attempt used a K061000 belt.

The Final Belt Routing:

A couple weeks after the completion of the project, I measured belt length again and decided that a K061066 belt is ideal. From the previous experience, I had little trouble to find the correct belt right away.

The Bracket:

The following images are showing the bracket built to hold the York comressor tightly in place.
Again, this bracket was built for the non-HO I6 engine, which differs considerably from all other XJs. However, the principal idea remains the same.
The bracket's crude appearance has to be blamed on a very limited amount of time (over night! My other ongoing project at the same time, a 4.7L stroker engine had to move on since I was blocking my friend's garage.)

Remember, this is the bracket for a "non-HO" ('87-'90 XJ/MJ). A custom bracket for the HO engines ('91+) will require a different mounting design.

Start with building the big "L" bracket.
Ideally, a 5" wide, ~1/4" thick, plate, bent in a 90 degree angle will accelerate this project considerably.
At the time, all I had available was a 12"x4"x1/4" plate that I widened with a 1" wide and 1/4" thick piece of metal. Possible, but not exactly a speedy method!

The 5" wide and 1' long plate.
The weld can be seen here where I filled in a little Bondo along the weld where I I removed a little too much with the grinder after welding.
> The relative smooth surface was achieved by using a belt sander and a relatively grainy sanding belt.
Also shown here is the first set of bolt holes.

Plate mounted to the York compressor to determine where to make the cut.

The plate is cut. Before welding them back together in a 90 degree angle, it appeared best to (spot) weld them while mounted to the compressor.
> Shown here is the second half of the plate with some tape on it. I placed the York under my shop press with that piece of the plate underneath it. Then with some pressure, the York's foot print was imprinted in the tape. That allowed to match precisely the bolt holes. However, after all the welding was done, some distortion necessitated widening the bolt holes a bit at the end.

Spot welding the two plates.
Notice the little gap. This allowed for a a solid weld from both sides with a 110V Lincoln 125+ welder, using flux-core wire. I ran a bead "full power" from both sides of the bracket.

Welding and grinding completed.

Next, the mounting pieces are pre-fabricated.
The idea behind this is, to mount the mounting pieces to the engine (such as the Sanden mounting bracket in the engine bay). Then position the York (whith its L-brace) and then tack-weld the mounting pieces to the York's L-brace. This is where the HO engine differs significantly from the non-HO engine used here.

Notes on measurements for the upper and lower mounting pieces. Good fit is critical for success.

The upper mounting piece is done. A longer bolt is necessary, but those are readily available at any better hardware store.

Now it is time to get both compressors ready for the final tack welding of the York's mounting pieces. The trick is to get the York perfectly aligned to fit into the existing serpentine belt configuration.
The following images show the Sanden and York compressors side by side. Both were cleaned and repainted.
(DupliColor WP102 Graphite Wheel Coating worked absolutely great for this).

Here the York compressor in its L-brace gets aligned.
The upper mounting piece is mounted to the Sanden compressor bracket. The lower mounting piece is obviously not visible in this image.

It is not only critical to get the York's clutch pulley perfectly in line with the serpentine, but also it is important to get the York's pulley properly aligned in the other accessories' plane! Use a angle finder for this. Measure and align until this is as perfect as possible. Then tack weld the mounting pieces to the L-brace.

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Front view of the engine.

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A fresh electrode and a very, very steady hand (eventually) did the trick.

Upper (red) and lower (blue) mounting pieces are tack-welded. Some extension pieces were needed.
(That bin with metal scraps come in very handy every once in a while).

Same as above, side view.

Time to add some support to the mounting pieces.

Same as above, side view.

More bits and pieces added to support the mounting pieces as much as possible.

The bracket is pretty much ready for some paint. Below more images from different angles.

Bracket painted. A bit of a rush project, but good enough for now. Below more images from different persectives.

Final checks.

• Belt straight? Yes.
• Pulley in same plane as rest? Yes.
• Good! The tough part is done.

York compressor mounted. Approximately in a 45 degree angle.

York compressors can be mounted from -90 to +90 degrees. I.e. Sideways, either side, and of course up-right). The pulley can be driven either direction, btw.

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This particular setup required the relocation of some of the A/C related hardware. While fitting the York compressor, the A/C hoses were missing. That caused intereferences with the lower hose to the receiver-dryer. The receiver-dryer was relocated. Some custom hoses were fabricated. This may or may not be an issue if properly considered ahead of time.
> ;-)
Shown here is the crimping tool for A/C hoses.

Final installation of all A/C hoses and A/C related hardware.

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Time to locate some room for the hardware to control the compressed air coming from the newly installed York!
Shown here is the heavily modified original water bottle tray, a remnant from the days when this engine still had the pressurized cooling system. The tray was kept with the on-board air conversion in mind. This proved to be a good idea!

Before tightening down all the fittings, here a final test fit on the tray (shown above).

The final assembly!

• A: This is the hose connected to the "DISCH" port of the York compressor, i.e. compressed air.
• B: The control valve. This is the one way valve that holds the pressure once the compressor shuts off.
• C: This copper tubing connects the control valve (B) to the switch (D). Once the compressor shuts off, the switch will bleed off the compressed air from the compressor to the control valve. This avoids that the compressor has to start against compressed air the next time it fires up. In the case of a York compressor this may not be a crucial feature, but clearly helps to reduce wear and tear.
• D: The switch. This is the same type of switch used on any typical home-shop type air compressor. The switch is mounted on its side here. Two bolts are used between the switch's housing and the above mentioned tray.
• E: Air pressure gauge.
• Above F: The safety relief valve (brass). This will open at 150psi in case the pressure switch (D) failed to shut off the compressor.
  This is an important safety feature!
  York compressors are capable of producing several hundred psi! This could cause severe problems if the pressure switch should fail.
  The safety valve also allows to quickly depressurize the system manually while servicing the on-board air system.
• To the right of F: This is an additional mounting point. This is a little u-bolt, acting as a clamp. Underneath it, painted gray, a piece of wood.
• G: An auxiliary port for future expansion. In other words, I am planning of installing a air pressure gauge in the inside of the cab. This will be the take-off for this gauge.
• H: Air hose to the right rocker panel air tank.
• I: Air hose to the left rocker panel air tank.

Detail view of the (black) switch (mounted to the black tray).
This switch has a manual OFF/AUTO control. In other words, it can be turned off manually. Notice the green LED that I added to better indicate that the switch in (AUTO)-on . A bit of gold paint further helped to make the OFF/AUTO stamped into the housing more visible.

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Detail of the gauge: The cut-off pressure is reached, approximately 125psi.

Detail of the gauge: Here's where the switch powers the compressor back on. I.e. at approximately 85psi, the York's clutch gets powered back on (power via a relay).

The above mentioned relay (mounted to the right inner fender and labeled accordingly.

Detail view of the safety valve. It will open if air pressure surpasses 150psi. This should be slightly higher than the rating of your pressure switch (in this case the pressure switch shuts power off at 125psi).

Detail view of the intake filter mounted to the salvaged A/C hose connected to the "SUCT" port of York compressor.

Looking inside the fenders. For a better idea of what this image shows, look through the article detailing the rocker panel installation. Shown here is one of the air hoses to one of the rocker panel air tanks.

The rocker panels.

Detail view of the rocker panel drain bolt. Will be replaced with a small NPT type hex plug, mountd completely flush with the end of the panel/tank.

The final system is installed. Shown here an overview of the engine bay (which is a heavily modified non-HO engine).

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• In-cab gauge
• In-cab manual override switch (electric switch to turn off the York if accidentally left turned on.
• Some type of automatic "idle up" funcition. In other words, every time the York kicks in the engine idle should be kicked up as well (to around 1200 to 1500rpm)
• Fix some minor leaks here and there.
• Truck air horns.

If you're planning to run air tools with this type of setup, make sure to add a large-capacity air tank (20 gallons). The 5 gallons used in this system proved inadequate for effective air tool use (such as a high impact air wrenches necessary to open lug nuts and hub nuts).

Here's another article dealing with on-board air that I really liked:
http://www.ohiomurals.com/jeepin/oba.htm.

Don't miss to check this one out! Possibly one of the best on-board air articles out there! It helped me a lot during the final steps of this project.