The recharge port on my 1999 F150 4x4 with 5.4L Triton engine is on the Accumulator. Accumulator is on passenger side firewall behind and slightly to left of engine oil fill spout. To see recharge port you need to look below plastic shield mounted on upper firewall. Port has plastic cover that unscrews and R134a can has quick coupling type connection. Port is angled toward driver's headlight. A flashlight will help considerably when looking for the port.
