Air compressor hiss

[lothos]

Quick question about the air ride in the back. I put the key in, turn the accessories on but don't start the car. After a short while I can hear the air compressor working. After it stops there is a hissing noise that I don't remember. Is this normal behavior, or should I look for a broken air line?

EDIT: I tried searching the forums and couldn't find anything. For all I know this is normal, I usually just turn on the car but I've been trying to diagnose an injector leak/bad fpr and have only been turning on the accessories without starting the car recently.

[Cadillac Jim]

I can't imagine a hissing noise coming from the rear of the car not being an air leak in the ride leveling system, but the first thing to do is to find out where the hiss is coming from and what it is. Try measuring the height of the rear bumper, putting a large toolbox or other heavy load in the trunk and measuring it again. Then, turn your ignition to Accessory and stick you head (or a baby monitor!) under the rear of the car to make sure that the hiss is coming from the rear. Watch the rear bumper height. If it comes back up to the unloaded position after the pump runs, then it's the air suspension. If it bleeds back down, then you have an air leak.

[Ranger]

Spray soapy water on all the fittings and air line connections. A leak will bubble like a mad dog.

[adallak]

Jack up the rear of the car so that you could see a fitting on a strut. Do just as Ranger suggested, covering those fittings with soap water. Probably you will hear hissing too. They are easy to disconnect, clean and lube the o-ring and put it back. There are other connections, but these two are easily accessible. Let us know what you find.

[lothos]

Thanks for the replies. I'm out of town right now, I'll check it out Monday after work and let you guys know what I find out. What should I use to clean and lube the o rings?