On my 1999 lincoln Navigator the rear bags are deflated.The compressor dose not start.And the light is not on.I know that it is activated by the doors is there also a switch on the hood. I was having a problem with the hood the other day and was slamming the hood to get it to latch. The next day the rear was on the ground and the compressor wont start.

SOURCE: 2001 lincoln navigator rear suspension?

Here is how to tell if system is working.Get into the vehicle and close door. Set ignition switch to on position and move the gear shifter to neutral. After a few secs. you should hear the compressor turn on. If it comes on then put shifter back to park leave ignition on and exit vehicle. Compressor will stop when you open the door but should start back up in a couple of secs. after you close the door. You can then walk around the vehicle and listen for leaks.
If compressor does not come on there are 3 fuses and a solid state relay that controls it along with the module.
The 3 fuses are no. 109(50amp) in the battery junction box under hood.This is the direct feed to compressor thru the solid state relay. The other 2 fuses are located in the interior fuse panel and they are no. 6 (5amp) and no. 12(15amp).
What we usually see though if compressor does not run is either a bad compressor or the solid state relay. They both are rather expensive so I would have an experience tech look at it then.
However If you feel confident enough and have a voltmeter or test light respond back and I will tell you which wires to check.

SOURCE: where is the air compressor on a 1999 lincoln

It is under hood right front

SOURCE: REAR AIR BAG SUSPENION

I would recommend going to strutmasters.com and taking a look at there conversion kits. these convert you from the airbag to a powder coated American made steel coil spring that is guaranteed to last the life of the car. Airbags and compressors are constantly having to be replaced. Also something alot of people don't know is that theses air suspensions are not meant to be in temperatures above 90 Degrees or below 40 Degrees. That is most of the world. The temperature will cause you to replace alot of bags. and typically when your replacing a bag you are going to have to replace the compressor to because the bag had a hole or small crack in it causing the compressor to over work and it will die. I posted the link below so you can take a look http://www.strutmasters.com/lincoln-suspension-parts-s/1.htm I hope I was of some help Good Luck!!!!

SOURCE: 1999 Lincoln Navigator ABS warning light turns on?

One of the ABS sensor's is bad or a hub bearing is bad.Could be front or rear.

SOURCE: I have a 2000 lincoln navigator, 4wd, and my rear

If you can get them inflated there is a switch on the passenger side that you can put in the **** off position till you get the problem resolved. Yet there is a part that is an inline part that can be leaking and must be replaced coast about $30.00. It is located in the engine compartment on the left side fender wall. It is in a airline that feeds to the Air suspension.What I did for a quick fix was a took the line apart place a 3/8 hose over it and clamped it. I have the part and never installed it because the above worked for me. Yet I do here the pump come on more often yet I was told the pump was bad. If you need to contact me email [email protected] or call 386 252 9987 fax will pick up on the 4th ring. I have a busy day tomorrow but try me later on in the afternoon 4ish. But email with the time you would be calling or leave your number. This information I am giving you cost me $500.00 to get.