Air conditioning is blowing cold air out of the passenger side and hot on driver

First - it could be indeed a leak of the refrigerant, but it seems odd that they would select the evaporator as the failed part unless it could be visually confirmed. Because the evaporator is concealed within it's case, it's nearly impossible to determine that there is any evidence of leakage here. I would suggest a second opinion. Furthermore -- if it is a major problem like this, appeal to the management of the dealership service department to ask Ford to assist you in the cost of such a costly abnormal repair on a vehicle so relatively new. If not, contact Ford's customer assistance center at 1-800-392-3673 to appeal on your own.