I have a 99 ford expedition eddie bauer eddition. the verhicle had a hard shake to it, and my friend told me it was the transfer case, i found that one of the tires was the wrong size, and replacing it fixed the issue, then it would happen every now and then if my tires went low on air pressure, but filling them up resolved the issue. now its stuck not working right, and the tires all match, and the air pressure is good, what could be the problem short or getting a new transfer case?

SOURCE: location of air conditioner low pressure valve

The low pressure valve on the 01 expedition is located on the accumulator on the passenger side fire wall. The accumulator is underneath the battery relay and a grouping of wires. Had to squeeze hand underneath a heater hose and an a/c line to remove cap and hook up hose. Nothing has to be removed to locate the valve just a little touchy feely. Valve faces a 45 forward toward the engine.

SOURCE: The air ride on my

look at the height regulator on the axle, my guess is that its broken loose

SOURCE: I have a 2007 ford

The original tire size the vehicle came with should be on a sticker inside the driver or passenger door jamb along with manufacturers suggested tire p.s.i.