Second air ride suspension compressor

[wrangedog]

Hello,
2003 H2
Replaced air ride compressor (Arnott), airlines, and air shocks, in January 2012. Dealer installed and programmed control module due to upgrading to the dual compressor system.
Worked great for over a year. One day left rear was sagging with "service air suspension" warning on DIC. Took to dealer and for 530.00 they adjusted torsion bar and realignment of the front end. One week later whole ass end sagging with same warning on DIC. Took to dealer and was told it needed a new compressor for 3800.00. I ordered new GM compressor (not Arnott) and it came with new control module, i also ordered all new lines. when i removed the old compressor i noticed that one of my air lines was sitting on the exhaust and melted through. I'm sure this is just a coincidence that the dealer had worked on my rear suspension a week prior. however when he told me the air compressor burned itself out he never mentioned the melted air line, and said "these things just burn themselves out."
When I powered up the new compressor it came on and the rear end inflated some but then stopped. the warning did not come on. I assumed because of the new control module the dealer would have to reset the ride height.So not trusting the dealer i put my old dealer programmed control module back on and i still have the same issues. the rear end is sitting low (but does not appear to be all the way down, it is somewhat drive-able). i have scoured this and other forums and have disconnected the battery, which seems to turn off the warning but it does come back on after a minute or two without the compressor running. i was under the vehicle and one of the compressors tried to run for a split second and then stopped. i have checked the fuses and the relay and all seems good. any suggestions would be greatly appreciated, i really don't want to go back to the dealer that i think i'm going to lodge a complaint against. thanks for any help or guidance

[HummerJim]

$3800 for a new compressor? That's why they call them stealerships! I think dealers see a Hummer with the air suspension and use the shotgun approach. It's not that complicated, sensors tell the pump to inflate one of the air bags. Bad, muddy or corroded sensors or a broken or cracked air line seem to be the most common problem areas with the air suspension. If you fix it yourself I'd go to another dealer to reset your DIC warning. I found an old thread here where they said they reset the DIC by disconnecting the battery for 30 minutes, but Humtech would know best. That's one reason why so many people have gone to springs in the rear.

[wrangedog]

Thanks for the reply, i did try disconnecting the battery. It did appear to clear the DIC warning however the compressor never came on and after a minute or two the "check air suspension" warning reappeared. Odd thing was that with the battery disconnected i did not have to reprogram my radio, or reset the clock.

[wrangedog]

HummerJim gave me an idea and i checked the ground going from the compressor to the chassis. as i started to loosen it, the compressors tried to come on. i disconnected the power to the compressor and cleaned the chassis with a wire wheel. still nothing, but it did get my hopes high. i just disconnected the battery again to see if clearing the warning makes a difference now.

[wrangedog]

OK, reattached battery, as soon as i attached positive it sounded for a second like the compressor started. but only lasted a second. started the engine and no warning, but compressor still not working. after a minute or so the warning came back on.
i am wondering if there can be a short somewhere because when i started to remove the ground i saw sparks and the compressors sounded like they were going to run. does anyone know if there is a way to test this, or if maybe this could be a symptom of a ride height sensor? thanks to anyone that can help.

[Easy Ed]

Just a thought, yours is a 2003 as is mine, pulled mine out because I got tired of the problems I was having, when I pulled it all out I found a "air inlet filter" tucked up in the rear drivers side fender well that was rusted up and it turned out that it restricted air going into the compressor so it would shut down the compressor after a couple minutes of running, then next time I would start the truck and it would do the same all over again. May not be your problem but if the compressor cannot get air to push into the bags it will shut down.

12th post down in the link below.

http://www.elcovaforums.com/forums/s...ad.php?t=24471

Good luck and if HUMTECH does read this he will try to help you out also.

Ed

[wrangedog]

Thanks for the input Easy ED, with this new compressor i replaced the air inlet line and the filter after seeing your post on the subject, and since i had not replaced it with the last compressor. Funny thing is i took my old one apart and it looks brand new, i'm almost worried it wasn't working.

[wrangedog]

*UPDATE*
Took truck to a second dealer, they diagnosed the problem as faulty left ride height sensor $148.00 (the same one the other dealer replaced 4 years ago), and the harness for that sensor $120.45, $235.90 for labor plus $40.35 tax for a total of $544.70. Add that to air lines, compressor and control module for $1,651.42 for a total of $2,195.77. Odd it was the sensor on the same side that was initially sagging. On a side note I attached 12 volts to the compressor that the first dealer said was burnt out and it seems fine.