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97-04 Ford F150 - Heat and AC Blend Door Replacement Parts

Video now online with additional information

  This is a product developed by the HeaterTreater Engineers for the common blend door failure problem on 97-04 F150 pickup truck. There was some crossover on the HVAC system used on the F150 and F250-450.  The difference between the two systems is the placement of the HVAC blower motor.  On 150's it is generally located under the dash on the passenger side, and on 250+ is mounted on the firewall in the engine compartment.  The listing is for the system with the fan motor inside the passenger compartment.  Check our F250 listing for the other variety.

 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.

This is a kit to do a complete repair on the blend door malfunction that is common to 97-04 F150's.   Every F150 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 opening...no 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 two 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 box", 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 F150 is built with a Blend Door to control the heater and AC function.  On the F150 all air flows through the evaporator core which can be switched on or off to provide cooling.  The air can now flow directly into the vent system or be diverted through the heater core by the blend door.   The door is controlled by a stepper 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.   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 temperature control knob on the HVAC control panel, 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. 

1.       Remove the bottom skirt that runs across the transmission tunnel.  It is held in place with plastic push pins.

2.       The system will look like the photo below.  On the bottom is an electronic control module with a vent tube on top and then the actuator motor and heater plenum box.   (Note:  we have received customer feedback that  early F150's may not have this electronic module and the heater box is placed closer to the floor boards over a distribution vent.  The vent distributes hot air to the passenger and driver's floor boards and is not a high pressure or structural element.  The F150 was not designed with HVAC repair procedures in mind and you may have to get "creative" to get the distribution vent out.  It can be hacked with a dremel tool and patched with aluminum duct tape.  The hack is out of sight and not a critical function, so you can do this with no functional or cosmetic impact.  I'm afraid you're on you own getting it out, but it's a normal kind of DIY challenge that you can figure out.)

3.       The electronic module is held in with three(usually green) screws.  Remove the screws and the module slides out toward the drivers footwell like a drawer.

4.       If you have the electronic module, the vent is easier to remove.  The vent is held in place with two screws.  One in the output on the driver's side and the other next to the firewall. 

5.       In the picture you can see an inverted water tank.  This is a vacuum actuator held on with two screws.  If you remove this, it is easier to remove the vent.  It has a wire hook that it attaches to and you need to watch carefully how it is attached so that you can reassemble it correctly.

6.       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.

7.       The connector on the blend door will look like the picture.  It is common for a handful of black plastic fragments to fall out when you remove the motor.  This is a conclusive indication of failure.  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.

8.       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 F150, cuts are required inside the heater box 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 hour.  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.  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 F150.

Patent Pending

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