Were is the location of blend door actuator on a 00 ford expedition your ac works fine in rear but only blows heat front no matter what selected?

On a 2000 Ford Expedition, the blend door actuator that controls the temperature of the air blowing to the front vents is typically located within the dashboard, behind the glove box. It's not easily accessible; you'll likely need to remove the glove box and possibly some other trim pieces to reach it.

Because your rear AC works fine, this strongly points to a problem with the front blend door actuator or its associated linkage, rather than a refrigerant or compressor issue. The actuator is a small motor that moves a door to mix hot and cold air. If it's stuck in the "heat" position, you'll only get hot air regardless of your settings.

Important Note: Accessing the blend door actuator requires some mechanical aptitude and familiarity with automotive repair. If you're not comfortable with this type of work, it's best to take your Expedition to a qualified mechanic. Improperly removing dashboard components can cause damage. A repair manual specific to your vehicle year and model would be extremely helpful in guiding you through the process.