1. Check the Electrical Connections:
- Locate the blower motor in your Jeep CJ7. It's usually mounted under the dashboard on the passenger side.
- Visually inspect the wiring harness for any loose connections or damaged wires.
- Ensure the electrical connectors are firmly plugged in and not corroded. If you find any loose or damaged connections, repair or replace them as needed.
2. Test the Blower Motor:
- Disconnect the electrical connector from the blower motor.
- Use a multimeter to test for power at the connector when the blower switch is turned on. If you don't get a voltage reading, the issue may be with the electrical circuit or the switch itself.
- If there is power at the connector, use the multimeter to test the continuity of the blower motor. A faulty blower motor will show no continuity.
3. Check the Blower Switch:
- If you confirmed power to the blower motor connector but it still doesn't work, the problem could be with the blower switch.
- Remove the blower switch and check for any loose connections or damage. Clean the switch contacts if necessary.
- Test the continuity of the switch with a multimeter to ensure it is working properly.
4. Inspect the Blower Resistor:
- The blower resistor controls the speed of the blower motor. If the resistor fails, the blower motor may not work at all or may only operate at a single speed.
- Locate the blower resistor (it's usually near the blower motor).
- Check for any signs of damage or overheating, such as melted plastic or wires.
- Test the resistor using a multimeter to determine its resistance. A faulty resistor will show infinite resistance or a significant deviation from its specified value.
5. Check for Vacuum Issues (if equipped):
- Some Jeep CJ7 models utilize vacuum-operated heater controls. If your vehicle is equipped with this system, check the vacuum lines and vacuum actuator for proper function and leaks.
Additional Tips:
- Consult your Jeep CJ7 repair manual for specific instructions and wiring diagrams related to your model and year.
- If you discover more complex electrical issues or mechanical problems, it's best to seek assistance from a qualified mechanic or auto electrician.
- Always practice safety when working on electrical components, such as disconnecting the battery before performing repairs.
By following this troubleshooting guide and conducting thorough electrical and mechanical checks, you should be able to diagnose and resolve the issue with the heater blower in your 1985 Jeep CJ7.
