A/C fully charged, won't work, Dash says outside air temp -40 degrees

That sounds like the problem, and it sounds like it may even be unplugged, since it is reading a default temperature. Check in the front grill area, someplace that is exposed to the outside temperature.

The outside temp sensor is mounted on the drivers side in the plastic fascia near the fog lite. It is a black tublar shape about 2" long with a blunt rounded nose. Two wires through a connector to disconnect it 5 minutes to replace it