Review on 🚗 Dorman Air Suspension Compressor 949-099 for Cadillac, Chevrolet, GMC - OE FIX by Michael Briggs

This review may seem lengthy, but I want to detail the process I went through updating the rear suspension components on my 2007. Avalanche with some tips I learned along the way that I couldn't find answers to in other reviews to help people with my shoes in the future. I recently replaced the rear shocks on my 2007 Avalanche LTZ on an Air Ride (about 140,000 miles on it) with Arnott Industries remanufactured AS-2708 shocks (from original cores) with the expectation that they would easily adapt to the existing supercharger and let the wiring connect that she and did. The day after I changed the shocks, I noticed that the right shock had an open piston between the airbox portion of the shock and the upper bracket. I assumed the remanufactured muffler might be defective and contacted Arnott who advised that my compressor might not be powerful enough to keep the mufflers at the desired pressure and level. The one on the left did not exhibit this behavior because the air line to this damper from the compressor is only 6 inches long at its bright rear mounting position, not a few feet on the right side. Arnott advised me to pressure check my compressor, noting that it should be 135psi. With calls across the city, none of the local shops or dealers were able to do this without a gauge adapter. While my original supercharger and shocks seemed to work fine, the supercharger was quite noisy and would come on for 20 seconds every time the truck started, was parked, or even was idling at a stop light. Loading the body with wood in November proved that while the original shocks could hold enough pressure to keep the truck level and didn't set up Stabilitrak fault codes, they obviously couldn't function under load with sharp rear wheels. Sag and the compressor runs all the way home, requiring the damper to be replaced with a new one. I had two options: remove the new damper, put the original damper on temporarily and wait until I send the damper back, get a replacement and go through the process again, with the possibility that it was indeed the compressor and went through the process for nothing, OR try replacing the compressor. First I decided to replace the compressor. From my selection, the Dorman 949-001 seemed like a much easier repair/replacement than the compressor offered by Arnott since they just give you the compressor itself. You have to use a used one from your truck for parts like mounting pan, ducts, bolts, nuts etc. I was able to do it myself in the driveway without lifting the truck. The compressor is mounted on the truck frame just behind the left rear wheel and under the fuel tank cap. The work took about 45 minutes. You will need a 13mm jack, an extension cord, a flathead screwdriver and needle nose pliers to remove the power/electronics connector.1. Disconnect the air ducts to the outside (the left muffler can be detached at the muffler, the right muffler can be detached at the compressor, Dorman will include a new left damper) and the air intake for the compressor (I just cut mine, there is a plastic bracket). which is a small air chamber at the end of the intake hose that attaches to a fuel tank that I couldn't get to and my regular mechanic installed a new one, took 2 minutes with a hoist, could have done it myself, lots of time but I didn't want to break it) not damage the connectors and terminals.3. There are three screws holding the unit to the frame, all of which fit into slots cut in the frame and then tightened. Socket 13mm. Use an extension. Two nuts are exposed and have enough room to work, the third nut is actually in the frame rail, accessible through a hole on the inside of the luggage rack (next to the spare wheel, needs a socket extension but no more than a few inches long, there isn't plenty of room to work if you don't drop the spare tire). Loosen all three nuts and with a little motivation the compressor should disengage and slide up and out of those slots towards the back of the truck. The device must be free at this moment.4. Loosen the nuts on the new block by removing the nut on its own bolt. Insert the compressor into the grooves in the frame. Tighten the two rear nuts. Install a new thru-bolt nut into the head, being careful not to lose the nut in the guide frame. Tighten all three.5. Snap the mains/electronic plug into place6. Connect air lines.7. Install the air intake hose/air box assembly to the bracket on the fuel filler neck.8. Start the truck, check the error messages on the dashboard. (I didn't have them before the replacement, if you have them and they're still there after the repair, you may have to drive a bit to clear them, or you may not have properly unplugged the power/electronics connector.), Dorman's new compressor is much quieter than the factory compressor, it doesn't run as often as it used to (and a lot less time when it does), and most importantly, it solved my problem. Vacuum in the right shock absorber. Since then, the handling of my Avalanche has improved significantly.