Refrigerant System Dye
WARNING: This page is about a different car, the 2016 Ford Transit Connect. However, it is still accessible from the selected car via links, so may be relevant.
A fluorescent refrigerant system dye wafer is added to the receiver-drier desiccant bag at the factory to assist in refrigerant system leak diagnosis using a Rotunda-approved UV blacklight. This fluorescent dye wafer dissolves after about 30 minutes of continuous A/C operation. It is not necessary to add additional dye to the refrigerant system before diagnosing leaks, even if a significant amount of refrigerant has been removed from the system.