Where is rhe air temp. Door actuator in a 2003 ford 450 truck

mode door actuator inrear Hvac . The clicking is the actuator slipping it's gear's . Plastic gears break ,wear out etc....
You have to take right rear trim panel out to replace it >
2003 2006 Ford Expedition Rear HVAC Temperature Blend Actuator Clicking... Your having problem with the mode door actuator ,not temp blend door.

there is an actuator that controlls a blend door that is called a blend door actuator. This "door" is inside the evaporator case and it opens and closes to divert air over either the evaporator (for air conditioning) or the heater core (for heat) and can be somewhere in between for warm air. your temp knob sends an electric signal to this actuator to controll that door. the actuator has plastic gears inside of it that can become stripped of its teeth causing a "tapping" sound. These trucks comonly have this problem. The actuator is screwed on to the evaporator case and the blend door actuator is a mounted on top either behind the radio or the glove box. It;s about the size of a deck of cards

Air/Blend Door Actuator Modual is defective: See info below
Description : Temperature Actuator Attributes : Controls the blend of hot & cold air Make : Ford Brand : Dorman - OE Solutions
Application Notes:
Please select Detailed Applications
for Application Note information.

You need to replace the blend door actuator, a very common problem on the Expys. Remove the passenger side interior panel, between the middle and rear seats. You will also have to unbolt the seatbelt - overall not a hard job. Just remember to have the gears on the new actuator set in the correct position as the one you pulled out or the door will tend to overtravel. ]
There are 2 actuators in that area, just to on the rear air to find out which one is making the problem.
The gears in the actuator are plastic and strip very easily, making the sound. I found a replacement at Advance Auto, but Im sure most parts houses have them.

Clicking sound is your blend door actuator stripping it's gears and failing to open the door that directs the blower air through the heater core. Follow the sound to the actuator and remove it. Install a new one. You may have to remove some panels to get to it. The part is shown below and costs $32 at autozone. Please let me know if you have questions.

could be door actuator for the temp or mode door or a/c needs to be looked at for possible leak my money is on a door actuator, please let me know

The problem you have is that the temperature control door is not actuating. This is the air blend door in the box under the dash that houses the heater core and the A/C coil. This door allows the different air temps to come through depending on your settings. The temp door is either stuck or the vacuum pod is bad. Have it replaced and that should get you back in business. Good luck.

a clogged heater core, a bad temp blend door actuator, or a damaged temp blend door

it has a vacuum actuator for the temp control. it could be going bad. that is what opens and closes blender door

It's the temp blend door actuator.