Owners of 2010 Ford Expeditions, F-150s and Lincoln Navigators with 5.4-liter engines may complain that their a/c system isn't producing enough cold air.
Once you open the hood, you may find that the system's pressure relief valve has been discharging refrigerant.
One likely cause, says Ford, is the electric cooling fan strategy isn't allowing the fans to come on quick enough, long enough or fast enough during idling. That leads to insufficient airflow through the condenser and higher system pressures, which ultimately leads to the relief valve expelling refrigerant.
Ford's two-pronged fix is to recover, evacuate and recharge the system to spec, then reprogram the PCM with an updated calibration that allows the cooling fans to draw more air through the condenser at idle, when it needs it most.
Check with a dealer for the specifics of the flash.