Where is the blend door actuator on a 2003 ford f150?

The blend door actuator on a 2003 Ford F-150 is located inside the dashboard, behind the glove compartment. Accessing it requires removing the glove compartment. There are often multiple actuators depending on the specific climate control system (single or dual-zone). You'll likely find it attached to the HVAC housing.

Important Note: Because it's behind the dash, accessing it is not a simple task. You'll need some mechanical aptitude and possibly special tools. A repair manual specific to your year and model F-150 will be extremely helpful in guiding you through the disassembly and reassembly process. There are also numerous videos online showing this repair for similar Ford trucks that might be beneficial.