1999 Lincoln Navigator

Suspension problem
1999 Lincoln Navigator V8 Four Wheel Drive Automatic 148000 miles

I have a 1999 Lincoln Navigator with air ride suspension. It now looks like a " low rider"! Just got in one morning and the compresser won't come on and interestingly enough, the rear wipers quit at the same time. I have checked all the fuses both inside the vehicle and also under the hood and they all are good. I don't know about the relay because I don't know how to check that. Any thoughts as to what the problem might be?
January 16, 2008.

The suspension compressor is run by the relay near the right headlamp, the wire colors are- lt blue/pink, lt grn/red, gray/red, dk blue/yellow. Find the relay and test for power at lt blue/pink, gray/red, if ok then test for ground at lt grn/red, dk blue/yellow. If all ok then check for power at the red at the motor and ground at the black and get back to me

Jan 18, 2008.