Ford F-150: How To Replace Your Blend Door

The blend door is responsible for the hot and cold air mix going in your Ford F-150's cabin. Here is how to replace it yourself.

By Thom Cannell - December 16, 2014
Contributors: Quintin, HeateTreater, TooTallGreg

This article applies to the Ford F-150 (2004-2014).

The blend door mixes the hot air with the cold air in the cabin of your Ford truck. If the door is broken, sometimes only hot air will blow through the vents, or similarly, just cold air. Here's how to replace the blend door yourself for under $200 and less than two hours of work.

Tools Needed

  • Screwdriver
  • 1/4" socket
  • 3/8" socket
  • Small pry bar

Pro Tip

The plastic post that is the actuator can bend or break, making movement impossible. A dealer will remove the dash and associated parts, which will cost you many hours and more dollars. Before buying a new blend door, assess whether or not the vacuum system in your diesel truck works. You can easily check the vacuum-controlled re-circulation by placing a Kleenex on the air intake between the windshield and the hood. It won’t move with re-circulation on, but it should move with it off.

Step 1 - Remove the glove box

While a dealer will remove the dash, evacuate the A/C and drain the heater, you can simply remove the glove box by squeezing the side in, releasing the tabs, and pulling down and out.

Figure 1. Remove the glove box.

Step 2 - Locate actuator motor

Pull and pry the three squeeze-clips (or remove the 5/16 screws) to remove the actuator.

Figure 2. Either the squeeze-clips or screws need to be removed.

Step 3 - Check the motor shaft extension

Examine the motor shaft extension for wear and breakage. Check that the blend door moves using a 1/4” socket to manually move the door, which should have about 60 degrees of movement. If greater than 60 degrees, the axle is likely cracked.

Step 4 - Cut the plenum box

Once convinced the blend door is your problem, cut the plenum open at the bottom to remove the blend door. Use a rotary cutting tool. Remove the old door and replace it with the new one, pushing the shaft up, reconnect the actuator motor, and properly index the shaft. Secure the cutout with metal duct tape, hot glue, or epoxy. Bondo and paint for a pristine appearance—or not.

Figure 3. Cut a square into the plenum box or remove the entire plenum box.
Figure 4. Under the plenum box you will find the blend door, heater core, and evaporator core.
Figure 5. Cracked end of blend door.

Pro Tip

Blend doors are available from auto parts stores or online from HeaterTreater and Amazon.

Featured Video: Blend Door Replacement

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