air conditioning will not work

You have not provided any information that can lead to a best guess. How do you know how much refrigerant is in the system? Ford uses quick-connect fittings on their hoses so they go together quickly on the assembly line. They always leak. Some systems need to have refrigerant added in as little as every two years.

If the compressor engaged once, it is a good bet the electrical circuit to it is okay. I would start by connecting a gauge set to see where the low and high-side pressures are. If the low side is too low, the compressor will be turned off to prevent potentially drawing in outside air with the harmful humidity in it. If the pressures are normal, the next best suspect is the computer controls.