The 1999 to 2004 WJ Jeep Grand Cherokees suffered from a design defect in which the blend doors for the HVAC system, which were made of plastic, would break at the actuator. This rendered the temperature control system inoperable. Until recently, the factory repair solution was an extremely complicated and expensive removal of the entire interior dash and HVAC system. Chrysler and private companies now offer inexpensive repair solutions by which you can replace the cheap plastic blend doors with solid metal units.
Park your Grand Cherokee on level ground and disengage the negative terminal on the battery.
Open the glove box and release the two glove box bumpers. Pull and twist to unhinge the box from the hinge pins. The blend door actuator sits behind the glove box.
Unplug the temperature sensor and blend door actuator motor. The motor is a black box in the left corner of the space formerly occupied by the glove box. Remove the blend door actuator motor, then remove the spindle underneath the motor with a set of pliers.
Outline and cut the outer blend door plastic using the template provided in the repair kit. The repair kit will contain a template you overlay over the plastic and mark out with a grease pencil. Using a 1/8 drill bit or a hot knife, cut the plastic out, using light force. The far right side of the glove box area is the evaporator, so take care not to drill into this area.
Outline and cut the inner blend door plastic using the template provided in the repair kit. Discard the inner door piece.
Grease the new blend door pivots with grease supplied in the blend door kit. Install the replacement aluminum door onto the spindle. You will notice the broken plastic door sitting in this area, which you should remove and discard. Replace the previously cut plastic outer door, using enough sealing tape to make an airtight seal. Reinstall the actuator motor, reconnecting the sensor. Note that the spindle motor may need to be rotated manually to align with the motor shaft.
Reconnect the battery. Confirm that climate control operation has been restored.
