Lincoln Navigator '97-'02

In stock

Failure of your heat and/or A/C in your Navigator is due to the failure of your blend door.

Heater Treater replaces the cheap, plastic blend door with steel. Replacing the blend door with the same plastic part from the manufacturer WILL result in continued problems — the same system design problem that caused the failure in the first place WILL happen again.

Heater Treater attacks the root cause of the failure by constructing hardware that is designed to meet the rigors of normal operation of the HVAC system, and last for the life of the vehicle.

If you feel uncomfortable installing the repair yourself, go Here to find a HeaterTreater certified garage near you.

Lincoln Navigator '97-'02
Lincoln Navigator '97-'02 HeaterTreater Ford F150 Part 1

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 temp control knob, and this is a common failure. Please check carefully before considering the blend door fix.

The blend door hangs on a vertical axis, so turning a sharp corner, or fiddling with the fan speed 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 Plenum box is the same as the F150 pickup truck and the Ford Expedition and video’s for those products will be applicable to your vehicle. The SUV’s are a little harder to work on than the trucks since you have to remove the center console between the front seats.



The Heater Treater Kit does the following:

  • Replaces the plastic blend doors and axle with steel components.
  • All work is done through the glove box 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 (purchased at any Target or hardware store).
  • 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 really easy and MUCH preferable to disassembly of the entire dash and engine cooling systems.
  • We provide customer support via email or phone if required.

 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 following videos demonstrate the Heater Treater installation process for all Ford Expeditions, Ford F150′s and Lincoln Navigators. The video demonstration is performed on the F150.

Our apologies in advance. The videos are amateurish and probably too long. Feel free to skip through the boring sections. It will take about as long to do the fix as to watch the video.

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.

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