1. Check the Coolant Temperature Sensor (CTS):
* Location: This sensor is usually located in the engine block or cylinder head, and its purpose is to tell the car's computer (or the fan's relay, depending on the system) when the coolant is hot enough to turn on the fan.
* Testing: You can test the CTS with a multimeter. The resistance changes with temperature. A faulty CTS won't send the correct signal, preventing the fan from activating. Consult a wiring diagram or a repair manual for the correct resistance values at different temperatures. You could also try temporarily shorting the connector to see if the fan runs (only do this briefly and cautiously – this is a test, not a permanent fix).
2. Relay:
* Location: The cooling fan relay is usually in a fuse box, often under the hood. It's a small electrical switch that acts as an intermediary between the CTS signal and the fan motor.
* Testing: You can swap the cooling fan relay with another relay of the same amperage rating (to make sure the relay itself isn't bad), or use a test light or multimeter to check for power going in and coming out. A bad relay won't pass the electrical current needed to power the fan motor.
3. Wiring:
* Inspection: Carefully inspect all wiring connecting the CTS, relay, and fan motor for any breaks, chafing, corrosion, or loose connections. A simple break in the wire can interrupt the circuit.
* Continuity Test: Use a multimeter to check for continuity in the wires. If there's a break, you'll get an infinite resistance reading.
4. Fan Motor:
* Testing: If you've checked everything else and the fan still isn't working, the fan motor itself might be faulty. You can try directly applying power to the fan motor terminals (with the fan disconnected from the wiring harness) using jumper wires connected to a battery. Be extremely careful when doing this to avoid short circuits. If the fan spins, the motor is fine; if not, the motor is likely the culprit.
5. Fuse:
* Check: While less common, a blown fuse in the fan circuit can also prevent the fan from working. Consult your owner's manual to locate the fan fuse and check if it's blown.
6. Low Coolant Level:
* Check: Make sure you have enough coolant in the radiator. A low coolant level will cause the engine to overheat, but the fan might not come on because the temperature sensor isn't reading an accurate temperature.
7. Thermostat:
* Check: A stuck closed thermostat won't allow coolant to circulate properly, causing the engine to overheat. It's possible the car is overheating before the coolant gets hot enough to trigger the fan via the CTS.
Important Notes:
* Safety First: Always work on a cool engine. Allow the engine to cool down completely before touching any hot components.
* Repair Manual: A factory service manual for your 1991 Camaro RS 305 is invaluable for detailed wiring diagrams and troubleshooting information.
* Professional Help: If you're uncomfortable working on your car's electrical system, it's best to take it to a qualified mechanic.
By systematically checking these components, you should be able to pinpoint the reason your cooling fan isn't working. Remember to replace any faulty parts with the correct specifications.
