Jeep Cherokee 1997+ Heat and AC Blend Door Replacement

This is a kit to do a complete repair on the blend door malfunction that is common to the 97- 01 Jeep Cherokee. Every Cherokee in this range either has, or will have, this common failure. The pictures show the hardware provided for the fix. All work is done from the foot area of the passenger side of the Jeep, with a Dremel cut in the bottom of the heater box...no removal of the dash panel or evacuating the AC system and draining the radiator. Once completed, the alterations are under the dash panel in the foot area 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 HeaterTreaterTM avoids the hard work by providing a kit that allows the repair to be done with superior components without having to disassemble the automobile. 1hr work vs 8-14 hours of work, and no specialized mechanical skills required.

The Problem:

- The Cherokee is built with a Blend Door to control the heater and AC function. The blend door controls air flow through either the AC evaporator or the heater coil, or any combination in between. The doors are controlled by a stepper motor. The issue with the system is that the drive motor has a wider range of motion than the movement of the door will allow. At the extents of movement(full heat or full AC), the motor overdrives the plastic blend door into the the internal stop point in the heater box until the motor stalls. This is considerable force on the door and over time, the door cannot withstand the force and will break. Once the door breaks, you lose control over the ability to regulate between heat and AC.

- The standard factory fix is to replace the plastic door. The process entails removing the heater box which requires - removing steering wheel and steering column, removing radio and all dash panel control modules, unbolting all attachment points for the dash panel, evacuating and disconnecting the AC compressor, draining and disconnecting the radiator, removing engine side bolts that hold the heater box in place. Once the box is removed, the fix is relatively simple, but you still have cheap plastic doors and the problem will occur again. It is not a particularly difficult fix for an experienced technician, but it is an 8-12hr job plus refrigerant and anti-freeze and the costs of labor and supplies adds up quickly into the $800-$1200 range.

Do you have the problem?

The usual symptom is an inability to effectively control the temperature of the HVAC system. 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.

The blend door actuator motor is located in the upper left hand corner of the passenger side foot well. The picture below show the location of the motor. The motor is attached with three 5/16"(or 8mm) screws that can be easily accessed and removed. Once you have detached the motor, you can turn the HVAC system on and observe the movement of the motor by turning the temp control knob. You want to make sure that the motor is moving properly. (if the motor is broken, we can help with a replacement).

The motor attaches to the blend door using two different connector schemes depending on the model year as shown in the second picture. You can grasp the axle with your fingers and feel the extents of movement of the door by turning the knob. You should be able to manually regulate between heat and AC by turning the axle. The door should hit a hard stop point when you turn it to heat or AC and not have any play beyond that point. If the axle is broken or feel disconnected from the door, this is a definitive indication of a broken blend door. It's hard to explain exactly what it feels like, but you should be able to switch from AC to heat and feel a solid stop at the max AC and heat positions. If the system is loose or ineffective, the blend door is the problem and the HeaterTreater is the solution.

The HeaterTreater Solution:

This kit replaces the plastic door and axle with stainless steel components that can withstand the force and will last longer than the Cherokee. All work is done from the passenger side foot well, 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(if you don't already have one, this is a good excuse and the tool has many uses. The area under the dash is confined and you will need either a stubby Dremel tool(~6” long), or a flexible extension for a larger industrial rotary tool. My favorite tool for the work is a Harbor Freight mini benchtop grinder with a flexible rotary cutter attachment. #43533. This setup has vaiable speed for the Dremel bits and is a good little bench grinder for fine metal and polishing work. ). Dremel bits, and all hardware is provided.

The repair will take about an hour the first time, and once you have experience, 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 from the bottom. Complete diagrams for the cutting pattern are provided. It's a very simple process. The broken plastic door is removed and replaced with the HeaterTreaterTM. 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 Wrangler.