Expert: Skip Bollinger - 6/30/2007

Question
QUESTION: I HAVE A 2002 ENVOY AND THE REAR END HAS DROPPED.  THE COMPRESSOR IS KICKING ON BUT NOTHING, I HAVE CHECKED THE FUSES, TIGHTENED THE SPARE JUST IN CASE IT WAS EFFECTING THE OVERLOAD SENSORS AND I HAVE DISCONNECTED THE BATTERY TO SEE IF IT WOULD RESET, BUT STILL NOTHING.  WHAT DO I NEED TO CHECK NEXT?  OR DOES IT SOUND LIKE I WILL NEED A WHOLE NEW SYSTEM?

ANSWER: P.
  Please slow down. Your question is all over the map. The rear of your Envoy had dropped, right? The compressor is kicking on so why would you check the fuses? You disconnected the battery to see if the system would reset. What do you mean, "the compressor is kicking on but nothing"? It is producing no air pressure or the air pressure is not getting to the suspension system? What exactly is going on.
  I suggest you relax. Sit down and write down exactly what you want to type. Read it to your spouse, Father/Mother, neighbor etc. Make sure it is clear as to what is working and not working. Send it to me again.
  I'm a Parts Specialist, NOT a Tech but I'm sure you will not need a whole new system. Just be calm and express the symptoms of the vehicle clearly. We are trying to diagnose a possible complex problem long distance. It would be like you call your doctor and tell him your arm hurts. Obviously he would want to see you but he would need to know as much specific information as you could give him over the phone to determine if it was bruised, strained or broken. This is what we are up against. Keep in touch and we will get this thing's butt back up in the air again. Thank you for your question..
Skip

---------- FOLLOW-UP ----------

QUESTION: OK, THE BACK END DROPPED THE OTHER DAY AND HAS NOT COME BACK UP.  IT SITS ABOUT 10 INCHES OFF THE GROUND.  JUST ENOUGH THAT THE TIRES DO NOT RUB. I CAN DRIVE THE VEHICLE BUT THE CAR BOUNCES LIKE CRAZY.  I READ MY OWNERS MANUAL AND FOUND THAT I HAVE AN OVERLOAD SENSOR THAT WILL SHUT DOWN THE SUSPENSION IF OVERLOADED.  BUT I NEVER PUT ANYTHING IN THE VEHICLE TO LOAD IT DOWN.  WHILE I WAS READING MY MANUAL, IT MENTIONED THAT THE SPARE TIRE UNDERNEATH NEEDS TO BE TIGHTENED AT ALL TIMES. BUT IT WAS LOOSE, SO I THOUGHT THAT MAYBE IT WAS EFFECTING THE OVERLOAD SENSORS SOMEHOW AND I TIGHTHTENED BACK UP WITH HOPES THE BACK END WOULD GO BACK UP.  IT DIDN'T.  WE CHECKED THE FUSES TO SEE IF SOMETHING WAS BLOWN CAUSING IT TO STAY DOWN AND NOT LIFT BACK UP.  BUT FOUND NO FUSES BLOWN.  ALL WERE GOOD.

THE COMPRESSOR STILL KICKS ON AND SHUTS OFF LIKE IT SHOULD BUT DOES NOT RAISE THE BACK END UP AT ALL.  SO I DONT THINK THE COMPRESSOR IS THE PROBLEM.  

DOES THIS HELP

Answer
P,
  Yes, that is MUCH better. Okay, the system consists of 3 basic components. The compressor, lines going to the air bags and the air bags themselves. I spoke to some techs today while at work and all agree there has to be a leak somewhere. One tech asked me if you had the truck put on a lift in a garage to have under chassis work done. She said that, on your truck, if you don't disable the air ride system when the vehicle is put on a lift or lift the rear of the vehicle, you can blow the rear air bags. They will not hold air and you cannot hear them leaking.
  With that being said, here is what I would suggest: take a measuring cup and a 1" paint brush. Fill a measuring cup with water. AFTER you have added the water, put in some dishwashing soap. You want a solution that will make bubbles but not have bubbles when you apply it. Climb under the vehicle and begin "painting" the solution on all the lines, fittings and the bags and watch for bubbles. Once you see the bubbles, replace that component. This is an old trick we used to use to find slow leaks in tires and it works, just be patient and don't work too fast. Don't forget to start the truck so the system is trying to work (compressor on and trying to pressurize the system).
  I hope this helps and solves your problem. The air bags are quite expensive, however. There is a company that offers replacement bags but not for your vehicle.
  I'm sorry for the confusion with our first encounter. I hope this gets you headed in the right direction. Please remember, in my Profile, I'm a Parts Professional, NOT a Tech but I have done the best I can, contacting my customers, to get an idea of what may be wrong and where to look. Good luck....
Skip