ARB CKMA12 On-Board Air Compressor High Performance 12 Volt for Air Locker Differentials and Tire Inflation

I permanently mounted this in my truck bed, it works great, inflates my tires and anything else quickly. This single unit inflates fast enough and I didn't want to spend so much on the dual unit. No other 12v small air compressor outdoes an ARB with the quality for the price.

I purchased this compressor to mount under the hood of my Chevy Colorado. I ordered the compressor and was surprised to have it the next day. I had used the free shipping that stated 5-8 days. I was very surprised. I opened the box to find the compressor and parts to be in excellent condition. The box contained everything needed for installation. It even had ring terminals and connectors to wire the harness to the battery. I was very happy with the wiring harness as well. The harness that is supplied with the compressor is designed for lockers, but I am using this compressor for tire fills. The harness was labeled very well and instructions were clear. I had no trouble with the wiring harness. The harness is plug and play. ARB even leaves one plug disconnected so only a small hole has to be drilled to get the switch to the cab area. I simply taped off the wires that I was not using. The wiring had a nice looking switch that is designed to be recessed in a small cut out. I found the switch to be good. The location I mounted the compressor was very tight, but the mount is made to pivot. I was unaware that the compressor body and manifold tube can also be rotated to facilitate various mounting locations. The compressor itself was heavier that I expected, but that was great. The compressor feels well made. I mounted the compressor and made the appropriate wiring connections under the hood. I actually mounted the switch under the hood as well. I used a small plastic gang box used in home wiring and used a Dremel Tool to route out a hole for the switch. I then used a metal plate to cover the box.I was then ready to use the compressor for the first time. I hit the switch and the compressor fired right up. The compressor only ran for about two seconds and shut down. The compressor comes with a pressure switch that shuts down the unit at around 90-100psi. The manifold tube is very small and it gets to that pressure very quick. The manifold tube also has a built in pressure safety relief valve just in case the pressure switch fails. I am not sure what pressure is required to permit the safety valve to operate.I had to source my own fittings to use the compressor as a tire fill unit. I did not purchase the kit offered by ARB because I can build it cheaper myself. I spent an additional $15.00 to make a manifold for my tire fill kit. I had to buy several pieces due to my mounting location under the hood. I also suggest to anyone that purchases the ARB tire fill kit to buy some Teflon tape. I completed the procedure and was ready to fill a tire. It should be noted that I already had 50 feet of 3/8 air hose and fitting to use the compressor. I wanted enough hose to reach from the engine bay to the tires on my travel trailer without uncoupling the trailer.I had been carrying a portable air tank in my truck that holds 120 psi. I decided to test the compressor by filling it up. I turned on the switch and watched the hose fill with air. The compressor then promptly shut off as designed. I filled my air tank from approx 40 psi to 90psi in approx 1 1/2 to 2 minutes. The compressor stopped filling at 90 psi. I was still impressed at the speed given the size of the compressor. I filled a car tire from 10 psi to 32 psi the next day and was equally impressed at the compressor. I think it was a wise investment and would buy it again if I had to go back.My installation took my friend and I two hours to complete. I had a small area to work with and had to "build" some tools to install some small screws in a tight place. I think my installation time was long, but I had a unique mounting location. Anyone with basic skills could install this compressor easily. I needed to drill three holes. The mounting plate has four holes, but I didn't use one due to mounting location restrictions.This is a good compressor and I hope to use it for many years. Good luck.

I have a 1998 Cherokee that has had an air locker of some sort since about 2000. For many years I had a Quick Air II compressor which served me well but not perfectly. I had several issues with it over the years. It finally quit completely about 6 years ago. After that I installed an on-board air compressor driven by the engine. This too turned out to have issues and I abandoned it. After that I returned to an electric compressor and bought a small Harbor Freight compressor just to run the lockers (all of my other setups were used for airing up and the lockers.)The Harbor Freight compressor turned out to be nothing but problems. Obviously you get what you pay for. The first one broke the pin on the crankshaft. I modified the compressor to use a bolt in the crankshaft and that fixed the problem. Then I had problems with it over heating. Finally one of the reed valves on the piston broke.I mention all of this to highlight all of the problems I've had over the years with something that is dead simple.I finally decided to quit messing around with junk and go with a compressor made by a company who specializes in air lockers and also has years of experience and a great reputation.Looking at the price of this tiny little guy I though it was very pricey for what I was getting. At the end of the day though, I've spent much more on unreliable and frustrating solutions.One major benefit, in addition to quality and reliability, is the fact that it is already set up to accommodate two solenoids and a pressure switch. I also believe you can get an air up kit for it if you'd like. I decided not to run an air gauge as I didn't feel I need one but I believe it will also accommodate one if you would like. In addition it includes wiring harnesses to connect everything. I cannot comment on whether they worked or not because everything was already wired by me from my past setups so there was no need to read invent the wheel.One thing I'd like to say is I don't think I would recommend the air up kit for this compressor. Not to use for airing up tires any way. If you were to use it for airing up balls and small items, maybe, otherwise get a larger portable compressor for airing up. Harbor Freight does make a larger portable compressor that looks suspiciously like a Viair and works quite well.All of this said, this is a great little compressor for running your air lockers. It airs up quickly and has plenty of capacity for this job. It is very compact which makes finding a place to mount it that much easier.After years of messing around with my air source on every wheeling trip it was nice to have a system that just plain worked and needed zero intervention! The price for this little guy may seem a bit high but in reality it is worth every penny.