Rawsong

Ok im new here and probally am going to only be asking one question from this forum. Ha but my familys down on vacation and they have run into an issue with the suspension. My dad said that they were driving and filled up on gas and then the suspension had stiffened up and the rear had dropped a few inches more then normal. So my guessing since im not there first hand is the air suspension bags got a leak? The air suspension compressor has gone out? The ride height sensor had gone wrong? or some other odd ball air leak? He had said he had a lot of just water/condenstaion from underneath the car but it wasnt from the AC he said it was from the front but im really un clear on what is going on with the car casue im not there. Any guesses anyone who has maybe experienced this problem first hand? Its a 2000 Ford Expeditoion XLT with the 5.4 liter trition motor and it is 2wd. Im just looking for some possible answer before he has to go the dealership and get screwed for triple the ammount that he should pay.

Thanks everyone