How do you fix the blower motor on a 1997 Jeep Grand Cherokee?

Answer 1

The heating and A/C blower motor is fairly easy to replace on the 1997 Jeep Grand Cherokee. There is some troubleshooting to do first because the issue may not be the motor itself. It could be the motor, the resistor module, the climate control system, the relay or the fuse.

I STRONGLY SUGGEST YOU READ THIS TO THE END BEFORE YOU START WORK.

Required Tools:

10mm socket

Short Extension

Ratchet

Pliers (slip joint)

#2 Phillips Screw Driver

Volt Meter

10 mm Net Driver (optional)

Inspection Mirror (optional)

Flashlight (optional)

Model Question:

Does this Jeep have Automatic Climate Control? The models with ACC have a digital temprature display and a variable speed blower with an "Auto Lo" and "Auto Hi" position on the speed selector.

Basic Troubleshooting:

Switch the ignition key to the "On" position and swith the blower to a medium position. Select the "Defrost" position. Do you hear the blower running? If the blower is running but no air is coming out, you probably want to research the diverter door - which can be a much more expensive problem.

If the blower is not running and you have the Automatic Climate Control system, is the digital display illuminated? If there is no display, check the fuse.

Assuming the display is working, the problem is either the fan, the resistor module or something in the control module (a switch or component failure).

The motor is located under the dash on the passengers side. It is oriented vertically, stick your head under the glove box and you will see the end of the motor hanging adjacent to the door panel.

Locate the two wires sticking out of the sie of the motor. Disconnect the connector. Connect the Volt meter to the wires from the resistor module that feed the motor. Switch the ignition to the "On" position, select the "Defrost" setting and set the blower speed to "High". The module should be putting out about 13 VDC.

If there is voltage, the motor is probably the issue. If there is no voltage, the more common failure is actually the Resistor Module. There are two different models of resistor module. The module for the Automatic Climate Control system is not really a resistor module at all - it is a solid state control module (the Borg Warner replacement is RU923 and it is about $150 from the auto parts store) The input to this module is a three pin connector with a B+, input and B-. The input wire comes from the ACC system module and it feeds 6-13 VDC to the Resistor Module depending on blower speed selected.

Disconnect the input connector from the module and connect the meter to the wires coming from the ACC system. With the igniton set to "On" the positive and negative wires (on either side of the connector) should output 13 VDC. Set the system to the "Defrost" position and the blower speed to the lowest manual setting. The voltage on the center pin should be around 6 VDC and should rise to around 13 VDC as you turn up the speed of the blower to the highest setting.

If the voltage is not present or changing, the issue is probably with the Automatic Climate Control system.

To replace the blower, remove the fuse cover from the body panel. remove the fastner that retains the plastic cover and remove the trip piece. Disconnect the vent tube from the bottom of the motor and disconnect the power connector. Remove the three 10mm screws that affix the motor to the ductwork. The assembly should be easily removed.

The blower wheel is held onto the motor shaft with a friction clamp. Squeeze the clamp with the pliers and slide the blower wheel off the shaft of the old motor and onto the replacement motor.

After 15 years, the blower wheel in my Jeep was pretty filthy. The motor brushes were worn out and dust was everywhere so I actually washed the blower wheel before installing it on the new motor. The new motor came without a connector but with two butt-splices. Rather than splice, I removed the connector from the old motor, used an awl to open the crimp legs and reinstalled the old connector on the new motor.

Reinstall the motor, reattache the three 10mm screws and reattach the vent tube.

Connect the power and test. You can also reaffix the trim pieces and reinstall the fuse box cover. Even if the module is bad, it can be serviced with the other parts in place.

I am not sure if the brush failure caused the module failure. But I had to replace the module too.

Replacing the Resistor Module:

The resistor module is mounted between the blower motor and the firewall. Use the inspection mirror and the flashlight to locate the two #2 Phillips screws that secure it to the duct. Remove the connectors and then remove the screws. Pull straight down. There is a large heat sink that extends into the ductwork about two inches. Install the new module and reconect the wires to the module and the blower motor.

Replacing the motor and the module restored the airflow. The total cost with the module and motor was just over $200. Total time is around 2 hours.