So far we've been told that the AC needs to be "charged" or that it needs to be replaced, but no one has suggested running diagnostics!

Most people are not familiar with EATC, which is very slick.

Keep in mind that compressors need to be replaced about every 100,000 miles--they do wear out. Also, never let anyone add freon who doesn't have a manifold gauge set. Stay away from anyone with a can of freon that comes with a gauge on it. It's best to recover the freon, evacuate the system (vacuum) for 30 minutes, and then refill with the specified amount of freon to the low pressure side of the system.

You are totally AWeSOME! I can't wait to show this to him. Hopefully I'll be driving in the Tennessee heat nice and cool soon!

Apparently the car needs a new compressor to the tune of about $1,000 and I can't afford that. However, while the mechanic was "checking it out" he filled with freon and said there was a leak. This was the 17th of August and the car is still blowing cold. Is this common?

On average, compressors last 100,000 miles. If you install a new compressor, empty the PAG oil that comes with it and refill with BG Universal Frigi-Quiet Refrigerant Oil (Part No. 7018). It's a superior product that will help your compressor last longer and perform better.

P.S. The majority of leaks in A/C systems are from the Shrader Valves in the low pressure or high pressure ports. Mechanics damage the valves by not attaching their manifold gauge set properly. Very easy to replace. These are often slow leaks because of the caps on top.

You should be able to buy a new Motorcraft compressor for around $370, BG Universal Frigi-Quiet Refrigerant Oil for $30, and $250 to recover, repair, evacuate, and refill the system.