1. Relay: The radiator fan is controlled by a relay. A bad relay will prevent the fan from working.
* Location: Check your owner's manual for the relay location (often in the underhood fuse box).
* Testing: You can visually inspect the relay for damage (burnt contacts, etc.). A better method is to swap the radiator fan relay with another (similar amperage) relay in the fuse box. If the fan works after the swap, the original relay was faulty.
2. Fuse: A blown fuse will also prevent the fan from working.
* Location: Check your owner's manual for the fuse location and rating for the radiator fan. The fuse box is usually located in the engine compartment or inside the car.
* Testing: Visually inspect the fuse for a broken filament.
3. Fan Motor: The fan motor itself could be faulty.
* Testing: You'll need to access the fan motor (often involves removing shrouding) and test it directly with a multimeter or by applying 12V power (carefully!) to its terminals. Caution: Always disconnect the battery negative terminal before working on electrical components.
4. Fan Switch/Sensor: The fan's operation is controlled by a temperature switch or sensor (often a coolant temperature sensor). This sensor tells the computer when to activate the fan.
* Testing: This usually requires a multimeter to check the sensor's resistance at different temperatures. A faulty sensor will provide incorrect readings to the computer, preventing the fan from activating. You'll likely need a wiring diagram to identify which sensor controls the fan.
5. Wiring: Problems in the wiring harness (broken wires, corroded connectors) can also prevent the fan from working.
* Testing: Visually inspect the wiring for damage. You may need a wiring diagram to trace the circuit and test for voltage at various points.
6. PCM (Powertrain Control Module): In some cases, a faulty PCM can prevent the fan from operating correctly. This is less common but possible. Diagnosing a PCM problem requires specialized tools and expertise.
7. Low Coolant: A low coolant level may trigger a safety mechanism that prevents the fan from running (to prevent overheating without coolant). Check your coolant level.
Troubleshooting Steps:
1. Start with the simplest: Check the fuse and relay first. These are the easiest to test and replace.
2. Visual inspection: Carefully inspect all wiring, connectors, and the fan motor itself for any obvious damage.
3. Check coolant level: Ensure you have sufficient coolant.
4. Use a multimeter: This is essential for testing the fan motor, temperature sensor, and wiring.
5. Consult a repair manual: A repair manual specific to your 1999 Chrysler Cirrus will provide detailed wiring diagrams, component locations, and testing procedures.
6. Seek professional help: If you are not comfortable working with automotive electrical systems, it's best to take your car to a qualified mechanic. A faulty fan can lead to serious engine damage if not addressed.
Remember safety first! Disconnect the negative battery terminal before working on any electrical components.
