Where is the lower service fitting for Air conditioning on a 1999 Ford expedition?

The lower service fitting for the air conditioning system on a 1999 Ford Expedition is located on the accumulator, which is typically situated on the passenger side of the engine bay near the firewall. It is the larger of the two fittings and is designed for the low-pressure side of the A/C system. To access it, you may need to remove some components for better visibility. Always ensure the system is off and properly depressurized before attempting to service it.