97 Lesabre, 3800 series II engine, 95,000 mi. Recently started with a "compressor" noise after approx 20 mins. of driving. Shut off, restart, OK for about next 20 mins. Low noise gets a bit louder as it goes. Can be heard over radio at "normal" volume. Any and all ideas???? THANX!!!

 

It would help if you could tell us where you think it is coming from. How about some help with a better description. Does it only happen while driving, any speed, does it seem to be coming from the back, front, left /right side, engine compartment ? Can you feel anything in the steering wheel ? Is there anything you do that makes it worse?

 

The noise is coming from the rear of the car, sounds like it is in the trunk. It sounds like a muffled mini compressor, similar to the the kind you plug into a cigarette lighter to fill your tires. It happens within a minute or so of starting the car. It is a constant noise. The tone/pitch/harmonic sound/frequency doesn't change whether the vehicle is idling in park or driving at any speed. It is not affected by acceleration/deceleration, turning, braking, or engine RPM. It never gets louder. However, I can change the tone/pitch/harmonic to a lower/slower sound/frequency by pushing the power window "up" buttons when the windows are already closed. Might this be related to the air-ride suspension? Is there any good documentation for test/troubleshoot/repair of the air-ride suspension? I might be guessing totally wrong as to the cause. Any and all help/input would be greatly appreciated. THANKS!

 

Your guess is probably on the money.
It could be the compressor trying to keep up with a leak in the system.
Check your owner's manual , there should be a fuse or circuit breaker that you can remove to confirm the noise/sound. If it does go away with the fuse removed , then you might start with a soap solution and spray around the air suspension components to determine where the leak is located, unless you can hear it without any help.