I'm not big on anyone but the dealers, as that's were I work. I have seen first hand what can happen when people that aren't trained work on A/C systems. Sure it may work for a while, but when it fails because of some shortcut that was taken to get it working cheaply, it's going to cost you big.
I would personally recommend that you take it to a Ford dealer. I know it's going to be expensive, but then again you have some piece of mind that it's going to be done right. It is true, dealers sometimes have people that don't know jack, again, i've seen that too, and in some situations you may be better off taking it a jiffy lube.
My recommendation, look around, ask questions, find out as much as possible about who you take it to. If you take it to a dealer, ask that whoever does all their a/c work gets your car. Working at a dealer, i know that we things get really busy sometimes jobs get pushed off onto tech's that don't normally get them, and this can lead to some issues. Don't mind waiting, if they are busy and only have one or two a/c certified guys it may take a few weeks to get it in.
If you aren't big on dealers, find a specialty shop that seems to only concentrate on a/c work. There are some great independent shops out there, and the ones that advertise being a/c specialists usually have trained personnel in that area.
A/C work is kinda hit and miss expense wise. If it's not kicking in, but has a good charge level it's most likely a simple electrical problem and won't be too expensive to fix. it's when you get into the refrigerant side of the system that it gets up there in cost. the average cost for a compressor is around $400, plus flushing $200, plus a drier $150, plus labor $400. you get the idea.
If you determine that your a/c has lost it's refrigerant and just needs recharged, it's not that simple. It lost it for a reason, it doesn't just get used up. It had to leak somewhere, and buying those cans of refrigerant at the parts store that look like fix a flat cans is a waste of time. Sure it'll probably get you going for now, but will eventually do damage to your system that will be some big $ in the end. Don't ever use STOP LEAK, EVER! this stuff is nasty. It works by coming in a can that you inject into your system. It works by hardening when exposed to air, that stuff gets rock hard. So, when your system eventually crashes, which it will as the stop leak messes it up over time, and the poor tech that comes along next to open up your system and replace components, the minute he cracks that system open all that sealer hardens and now the whole system is trashed.
Sorry bout that long rant, but this is just some of the things i've seen people do.
Basically, please, take it to a professional if you don't know how it works. You may fix it for now, it may work for 2 or 3 years, but in the end it's just not worth it guys.