* Blown Fuse: This is the easiest and cheapest thing to check first. Your owner's manual will show you the fuse box location and which fuse(s) control the cooling fans. Visually inspect the fuse for a broken filament.
* Relay Failure: The cooling fan relay acts as a switch, sending power to the fans. A faulty relay will prevent the fans from turning on. You can usually swap the relay with a similar one (often labeled as "spare") to test this. If the fans work with the swapped relay, you've found the problem.
* Fan Motor Failure: The fan motor itself could be burned out or have a seized bearing. This is a more involved problem requiring replacement of the fan(s). You can often test the motor directly with power (be cautious!) if you have a suitable power source and are comfortable with electrical work.
* Wiring Issues: A broken wire, corroded connection, or short circuit in the wiring harness can prevent power from reaching the fans. This requires visual inspection of the wiring, connectors, and the fan motor itself.
* Cooling Fan Control Module (CFCM) Failure: This is a more sophisticated electronic module that controls the fan speed and operation. A faulty CFCM is a more serious problem usually requiring replacement. A diagnostic scan tool can help determine if the CFCM is the culprit.
* Temperature Sensor Issues: The engine coolant temperature sensor or other sensors may be providing inaccurate readings, preventing the PCM (Powertrain Control Module) from activating the cooling fans. A faulty sensor will throw a diagnostic trouble code (DTC).
* PCM (Powertrain Control Module) Problem: Though less likely, a malfunctioning PCM could also prevent the fans from operating correctly. This is a more involved repair and usually requires professional diagnosis and potentially replacement.
Troubleshooting Steps:
1. Check the fuses: This is the easiest and quickest first step.
2. Check the relays: Swap relays if possible.
3. Inspect the wiring harness: Look for any damage, corrosion, or loose connections.
4. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to check for any codes that may indicate a problem with the cooling system or fan control. This is crucial.
5. Test the fan motor (with caution!): If possible, apply power directly to the motor (using the correct voltage) to see if it works.
6. Consult a repair manual: A repair manual specific to your 2005 Chevy Impala will provide detailed diagrams and troubleshooting steps.
If you're not comfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic for diagnosis and repair. Ignoring a malfunctioning cooling fan can lead to engine overheating and serious damage.
