What's going on with my a.c. in my Expedition?

Hello, does the fan sound loud, like it's operating at full power? It sounds like you could have a mode door issue, causing air to not blow in the proper area. Another thing to look at -- there's a chance your air conditioning compressor could be staying on for too long a duration. When this happens, the evaporator core can become iced over, preventing air flow. I would suggest having a close look at the compressor and see if the air flow diminishes as the air condoning system runs for a continual period of time.