Ford Expedition '03-'06

In stock

HeaterTreater kit for blend door repair on the Ford Expedition '03-'06. This kit will replace the door and restore heat and AC to the vehicle.  This repair is medium difficulty and well within the capability of shade tree mechanics.

Ford Expedition '03-'06
Ford Expedition '03-'06 HeaterTreater Ford F150 Video.wmv

Do you have the problem?


The usual symptom is an inability to effectively control the temperature in your car.  Note that this symptom can also be caused by a bad temperature control knob, and this is a common failure on Ford trucks. 


The blend door hangs on a vertical axis, so turning a sharp corner or turning up the fan to “blow the door shut” can swing the door into the hot or cold position randomly.  While the symptoms are fairly conclusive for blend door failure, the only way to really check it out is to remove the blend door actuator motor and look at the axle.  The actuator motor is on the top of the plenum box and extends through the bottom of the box and you can find the bottom of the axle and feel the movement when you change temperature.  If you want to really check closely, you can cut a “peephole” in the box and see/feel the movement of the door. Cut a small square section that will be easy to patch with some sheet metal and epoxy.



-       All work is done through the glove box and radio opening and no disassembly of the dash or evacuation of the AC system is required.

-       Tools required are a screw driver, pair of pliers, and a Dremel tool.  You can also use a hot knife(soldering iron with blade attachment).  This makes less mess, but is slow.

-       Includes detailed instructions and all hardware required to complete the fix, including dremel bits and metal tape to seal the cut.

-       The repair will take about an 90 minutes the first time, and once you have experience, about 45 minutes.

-       No extensive mechanical skills are required.

-       The instructions are dual-level, for mechanics and a “Instructions for Dummies” version.

-       The fix is relatively easy and MUCH preferable to disassembly of the entire dash and engine cooling systems.

-       We provide customer support via email or phone as required.

The following video demonstrates the Heater Treater installation process.  Note that this is a sample application and your dash/access may vary slightly,

Full instructions with pictures are included with the kit, so between the instructions and the video, the job should go fairly smoothly. From some of our customers comments, the hardest part is getting up the nerve to make the first cut into the box. Once you’ve made the commitment, the fix goes smoothly. If you ever have a reason to do a second repair, it will be very easy.

The motor on this model is on top and difficult to get to and check.  The video below shows the location and access.  Ford didn’t make any design provision for ease of access, so there is a little work to get to it and the connection is recessed in the box and hard to check.  The motor is a two wire DC motor and you can use a 9V radio battery and snap connector to check the motor by contacting the two outside pins on the connector,

The HeaterTreater kit will replace the weak plastic doors with metal components.  The system will operate just as new, only longer life and reliability and better sealing with the improved foam used on the door.  The repair will outlast the vehicle and save money over the dealer repair. 

Aluminum vs Steel air doors

We are the industry engineering experts on air doors and have been in business over ten years with multiple vehicle application.  Early on we evaluated aluminum doors and found some obvious and not so obvious issues.

-  Aluminum would appear to be lighter and less stressful on the actuator motor...not true.  As we all learned in Kindergarten physics, if you have a fat guy sitting in the center of the see-saw, it doesn't have an impact.  Rotational stress is a function of distance from the axis.  Our doors are heavier, but the bulk of the weight is in the axle which has no impact on required torque.  In fact, the added axle weight actually stabilizes movement.

-  The actuator motors have waaaay more torque capacity than required for this application, and actually is the root cause of the common failures.  We've been doing this across multiple models and have never seen an issue with motors wearing out or breaking with steel doors.

-  Welding aluminum plate is problematic and we saw issues early on with doors breaking at the periphery of the weld pattern.  Aluminum plate changes physical characteristics from the extreme heat associated with welding and becomes weaker at the weld point.  This is why aluminum plate is riveted, not welded on airplanes.  Welding is OK on aluminum structural components that can withstand the heat, but not plate.

-  Aluminum is "springier" than plastic and can vibrate in the air flow producing a humming noise.  It's generally not an issue or even annoying, but the resonant vibration can further weaken aluminum welds.

-  Our steel plate is more rigid and gives a more reliable and consistent seal against the extents of movement.


We’ve seen comments that my plastic door lasted 10yrs or more and I”ll just replace it with another plastic door and get 10 more years of service.  On the surface that sounds logical, but it’s not quite true.

The failure is due to the weakness of the plastic door and the torque applied by the actuator motor during the calibration process which is an automatic function that can’t be controlled.  The original battery in the vehicle was the minimum that the supplier could provide and lowest cost.  You never see a Ford advertisement that says “buy our vehicle because we use better batteries than Chevy”.  However, aftermarket battery sales companies want to provide a battery that will last longer and perform better since they have to stand behind their product.  It’s common to go from a 55CCA OEM battery to a 70CCA replacement.  You’ll notice brighter headlights, quicker starting, more start power on those cold days, and power windows that go up/down faster.

This impact also shows up on the torque applied during the HVAC calibration process and will break a new plastic door much faster than the original door.  The calibration is a function of on/off cycles of the engine and depending on usage, expect a replacement door to last only 12-18 months.  Even a metal connection on the replacement air door to the motor will fail because the plastic stop points on the box will break, transferring force to the plastic door again.  Our metal doors replace all the plastic components with steel and the doors are strong enough to withstand any forces that the system applies and will be a permanent fix to the system.  

If you are selling the vehicle and just want it to work long enough to get rid of it, cheap plastic is a viable solution.  If you need longer term performance, steel doors are the way to go!!


The video shows a Ford F150 installation, but the plenum box and repair are the same on the Expedition.

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