We have information on this site about onboard air. Here’s a look at how one of our members did it using his existing A/C compressor.

From: Forum Member escort_gts

Original Post: On-Board Air Using A/C Pump (Post from 05/13/18)

Here is my setup using the stock ranger A/C compressor.

Parts needed with prices. Prices are estimated:

  • 160 PSI max tank 5 gallons or equivalent $35
  • Inline oiler 1/2″ NPT $4
  • Manifold with at least (4) outlet ports 3/8 NPT inlet 1/4 NPT outlets $8
  • Pressure switch 90 PSI on / 120 PSI off 1/4″ NPT $10
  • Safety valve rated within tank max pressure, I used a 150 PSI 1/4″ NPT $5
  • 160 PSI gauge 1/4 NPT $12
  • Check valve 3/8 NPT $8
  • Oil / water separator 1/4 NPT $8
  • Quick connect air fittings 1/4 NPT with 3/8″ and 1/4″ hoses ~$10
  • DOT approved 3/8 air line
  • Miscellaneous barbed and other fittings ~$10

All parts except for brass fittings I got from eBay.

Total; roughly $100 but I got some of the parts for free. So my cost was less than $50

Here is the tank I used. It’s for a semi tractor.

I mounted it under the bed behind the axle where the spare tire was.

Had to weld brackets to the frame, was a little smaller than the frame width.

I plumbed the inlet into the air cleaner box. This way I didn’t have to use a separate filter. I used 1/2″NPT pipe with two locking nuts at the air box and then mounted the inline oiler to it. And then used 5/8″ heater hose from the oiler to the inlet tube for the compressor.

The inlet of the compressor is the top tube. Outlet is the bottom one.

From the outlet I just cut the hose and then used a barbed fitting and then mounted the check valve before the manifold. You can barely see it here.

I mounted the manifold to a bracket attached to the master cylinder. Then mounted the gauge, switch, safety valve and the outlet that runs the the tank with the oil/water filter.

I ended up using the factory a/c relay and used a toggle switch mounted on the dash. Have to open up the relay/fuse box and rewire it; from the fuse panel under the dash I found an unused acc on lead and ran a wire from that to the switch on the dash. From there ran a wire to the pressure switch located on the manifold, then to the relay. From the relay its already wired to run the clutch on the compressor.

For air fittings, I placed one on the rear bumper and in the grill. I used 1/4″ DOT air hose but I would like to switch it to 3/8 hose for more air flow.

This setup works great. I can run air tools and air a completely flat 35″ tire in a few minutes. Been using it for two years without any major problems. Only thing I had to fix was I originally used a cheap rubber air hose going to the tank. I had to replace the hose after a year because it rotted out from all the road salt. I replaced the hose with DOT approved 3/8″ air line.

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