Lincoln/Mercury Repair: air suspension issue, Expedition & Navigator air suspension problem, compressor runs for 90 seconds

Question
Hello Eddie,
I have a question in  reference  to my 2002 linc navigator 4x4 w/ 5.4l. After starting the truck the air pump comes on and stays on until the check suspension light comes on the dash. System stays inflated but the pump will not come on again unless I shut off the motor for at least 20 min. if I cycle the ignition it doesn't help. Is this something I could check myself? I poses basic mechanical knowledge.

Thank you Peter....

Answer
Peter, The first thing I would do is to first check the compressor for pressure output with a gauge specifically made for this. They are hard to find, as they must be fabricated. Most dealers don't even have one....as they usually "guess". BTW, the compressor has to make 120 psi "minimum". Keep in mind that you'll eventually lose some air in the system and it'll require more air. If the compressor is bad, it won't be able to raise up. Go here for parts:  http://www.americanairsuspension.com/cart/