* Blower Motor Resistor: This is the most likely cause. The resistor controls the different blower speeds. If it's faulty, it might only allow power to reach the motor at a certain speed (speed 2 in your case). A bad resistor often presents as only high speed working, or only certain speeds working.
* Blower Motor: The blower motor itself could be failing. While less likely to only affect certain speeds, a failing motor might struggle to operate at lower speeds due to worn components.
* Wiring and Connections: A break or loose connection in the wiring harness leading to the blower motor or resistor can interrupt the signal for lower speeds. Corrosion in the connectors is common and can cause intermittent or complete failures.
* Fuse or Circuit Breaker: While less probable in this specific scenario, a partially blown fuse or a tripped circuit breaker could restrict power to some blower speeds.
* Control Panel Switch: The switch itself that controls the fan speed could be malfunctioning, preventing the selection of lower speeds.
Troubleshooting Steps:
1. Check the Fuse(s): Consult your owner's manual to locate the fuse(s) for the blower motor and check them for continuity.
2. Inspect the Blower Motor Resistor: This is usually located behind the glove box or under the dash. Access it (refer to your owner's manual or an online repair guide), and visually inspect it for burn marks or obvious damage. You can often test it with a multimeter for continuity between the correct terminals (again, consult a repair manual or online resources).
3. Check Wiring and Connections: Examine the wiring harness to the resistor and blower motor for any broken wires, loose connections, or corrosion. Clean any corroded connectors.
4. Test the Blower Motor: While more involved, you can test the blower motor directly with power (use caution and follow safety guidelines) to see if it operates correctly.
5. Check the Control Panel Switch: This is the most difficult to test and often requires some electrical knowledge and diagnostic tools.
If you are not comfortable working on electrical systems, it's best to take your Jeep to a qualified mechanic for diagnosis and repair. Replacing the blower motor resistor is often a relatively inexpensive and straightforward fix if that's the problem.
