FJ Cruiser On-Board Air Compressor

After five years of airing up after an off-road adventure using my Harbor Freight mini compressor, I decided to install an onboard unit.  After a little research, I settled on the ARB CKMTA12 twin compressor.  This little unit will provide 100 PSI, continuous duty - enough to easily air up my tires and run an impact wrench.

After getting it installed and wired, I aired a tire down to 21psi (standard off-road pressure), and timed filling it back up to 46psi (standard on-road pressure).  Total time, barely a minute.  The next test will be with an impact wrench.

When I started planning the installation, I wanted the compressor in the engine bay and up high enough that dirt and moisture wouldn't be a problem.  I also needed an area where heat from the compressor would not be an issue with surrounding components.  And I hate drilling holes in my vehicles. Fortunately, there's plenty room in the engine bay of the FJ, and in the back corner there are some existing 8mm threaded holes in the fender area, which I could use to bolt on a bracket for holding the compressor.

I fabricated a bracket out of a piece of steel bar stock and some steel plate.  The bracket bolts into the side of the engine bay into two existing threaded holes, and to the bolt which mounts the cold air intake.  I welded a piece of steel plate to the bracket and drilled holes to accommodate the compressor.  A teflon air hose encased in braided stainless connects the compressor to a quick disconnect, mounted on the forward part of the bracket, making it easy to attach the air hose.

Wiring was really straight forward using the existing ARB wiring looms, and only required poking a small hole in one of the rubber seals where the wiring enters the cabin through the firewall.  I sealed the hole with RTV sealer after inserting the wire under the dash.  A 10A Add-A Circuit, placed into the fuse box in an empty slot that is active only when the engine is running runs through the ARB switch, mounted in an existing slot to the left of the steering wheel.  I routed all the cabling along the back of the engine bay, tucked up under the top against the firewall, secured with zip-ties, and connected power and ground to the battery terminals.

With this, I can quickly air up - which means I'll be more inclined to air down, which means off road the vehicle will be better, and I won't tear up the roads as much.  It's all good!  (When I attended the Toyota Trail Teams event a few years ago, one of the instructors said that for the good of the vehicle and the good of the trails, one should always air down and always run in 4WD).