blend door fix

97-02 Navigator/Ford Expedition HeaterTreater - Heat and AC Blend Door Replacement Parts

Video now on line with additional information

This is a product developed by the HeaterTreater Engineers for the common blend door failure problem on 97-02 Lincoln Navigator and Ford Expedition.  The system used in these models is the same as the Ford F150 pickup truck.  The difference in the fix is location and access to the blend door actuator motor.

 Please check our feedback to get an idea of the product line integrity and customer reaction to our products. We are committed to customer satisfaction and successful repairs of blend door problems. 

The HeaterTreater replaces the plastic blend door with steel. Replacing the existing door with another plastic door is at best a stop-gap solution. The failure is a result of excessive forces in the operation of the blend door.

Replacing the plastic door is only solving the symptoms of the problem. The same system design problem that caused the failure in the first place WILL recur over time. The HeaterTreater 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 SUV.  The kit includes detailed instructions and all hardware required to complete the fix, including dremel bits and metal tape to seal the cut.

This is a kit to do a complete repair on the blend door malfunction that is common to the Expedition and Navigator.   Every one of the models in this range either has, or will have, this common failure over time.  The pictures show the hardware provided for the fix.  All work is done through the glove compartment removal of the dash panel or evacuating the AC system and draining the radiator.  Once completed, the alterations are behind the glove box and are not visible.  The work to install the fix is relatively simple and can be accomplished by the average shade tree mechanic. The work could easily be done by any local independent garage. Product returns are accepted within three weeks for a full refund(minus shipping).

The standard fix for the blend door failure is to remove the heater box and replace the plastic door. If the instructions with other fixes start out with “remove the heater boxâ€�, be ready for considerable work. Removal of the box requires removing the dash panel, evacuating and disconnecting the AC compressor, draining and disconnecting the heater hoses. Fixing the door is relatively easy, but the labor(and cost) of getting to the door makes this a time consuming and expensive job. The HeaterTreater avoids the hard work by providing a kit that allows the repair to be done with superior components without having to disassemble the truck. 1hr work vs 8-14 hours of work, and no specialized mechanical skills required.  The cost of a new plastic door is cheap, but when you include refrigerant, anti-freeze, new AC line connectors, and the time to do the fix, the HeaterTreater is a cost effective solution.


The Problem:

-  The Navigator/Expedition  is built with a Blend Door to control the heater and AC function.  The blend door controls air flow through the AC evaporator or the heater coil, or any combination in between.  The doors are controlled by a DC  motor. The issue with the system is that the system has to calibrate itself and find the end points of movement before the computer can understand the two closed positions and regulate the temperature.  The motor has a larger range of movement than the door will allow. The net effect is that the plastic doors have to absorb the force of the motor driving to a stall point during the periodic calibration routine.   The motor is geared to move the doors slowly and with a good amount of force. The door has to withstand the force of stopping the motor, and like bending a coat hanger back and forth, will eventually break. 

Do you have the problem?

The usual symptom is an inability to effectively control the temperature of the HVAC system. Note that this symptom can also be caused by a bad temp control knob, and this is a common failure on Ford trucks.  Please check carefully before considering the blend door fix.  The 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.

Accessing the blend door motor is actually the most difficult part of the fix.  The actuator is located on the bottom of the heater box above the transmission tunnel.  There are different configurations across the two models and different years and we can't provide definitive instructions that cover all circumstances.  Here is the general process:

1.       Pull the center console if so equipped.  The picture shows an example of the dash minus the console.

2.       Remove the plastic skirt shown in the photo.

3.       Remove the floor vent that extends under the actuator motor.  This is the hard part.  This vent tube distributes heat between the floor on the driver's side and passenger side in heater mode.  It is not a high pressure or structural component of the system and if it leaks�, it's not a major issue.  The vent tube can be removed by unscrewing and wrestling with it or making a Dremel cut as shown in the picture.  The cut can be re-sealed with metal duct tape and may leak, but it's not a big issue.

4.       Once the pieces are removed, you can see the actuator motor.  It is held in place with three screws.  Pry straight down after removing the screws.

5.       The connector on the blend door will look like the picture.  Use a mirror to examine the connector for cracks or broken areas.  The picture shows an angle bracket that can be used as a key to turn the axle.  Any flat angled piece of metal ~1/2"� wide will work.

6.       The door should have 60 degrees of movement between the full heat and full AC position.  Rotate the axle to check the end points and see if the blend door is doing it's job.  You can turn on the HVAC system and check that you can switch between AC and heat manually.  Note that if the movement is greater than 60 degrees, the door is probably cracked and the computer system will detect incorrect end points and not fully close off the evaporator or heater core.

Another reported fail symptom is a clicking sound coming from the actuator motor. This occurs when the motor gears get out of alignment and are slipping against each other, making the noise. Sometimes you can make it stop by pushing down on the back of the motor and getting the gears to catch.  The failure usually occurs with a broken blend door that allows the motor to get out of alignment and twist slightly, causing the gears to disengage. The HeaterTreater will put the system back in alignment and correct this problem.


The HeaterTreater TM Solution:

This kit replaces the plastic doors and axle with stainless 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.  For the Excursion/Navigator, cuts may be required inside the heater box(dependent on the condition of the broken door) and a flexible extension for a Dremel tool is highly recommended.  Target has a new rotary cutter product from Durabuilt for ~$30 that includes a flexible extension, variable speed motor, and every grinding bit known to modern Chinese technology(except the one you really need which is included in the HeaterTreater kit)

The repair will take about an 90min the first time, and once you have experience, you could do a second automobile about 45min.  No extensive mechanical skills are required.  The picture shows the metal replacement kit.  The plastic door is accessed by using the Dremel tool and bit to cut into the plastic heater housing through the glove box opening.  Complete diagrams for the cutting pattern are provided.  It's a very simple process.  Note in the before and after pictures that there is a plastic divider behind the glove box and a minor amount of plastic that is part of the dash support infrastructure.  Both are cut in the process.  In our analysis, neither of these cuts affects the integrity of the dash, but we want to make sure that there is no misunderstanding with the fix.  The broken plastic door is removed and replaced with the
HeaterTreater TM

The instructions are written with multiple pictures and dual level instructions.  You can read the bold print only for experienced mechanics or read the bold and standard for full "instructions for Dummies".  The instructions are almost insultingly simplistic for those who care to read the entire document without admitting that they did it.  The fix is really easy and MUCH preferable to disassembly of the entire dash and engine cooling systems. We provide support via email or phone if required. Our goal is to make sure that every installation is successful. To date we have achieved that goal and have no intention of letting up. This will solve the problems with the blend door and is over-engineered to outlast the Expedition/Navigator.



Patent Pending