1. Check the fuses and relays:
* Locate the fuse box: Consult your owner's manual to find the location of the underhood and interior fuse boxes. The radiator fan will have its own fuse(s) and possibly a relay.
* Identify the correct fuse(s) and relay(s): Again, your owner's manual is crucial here. Look for fuses labeled "radiator fan," "cooling fan," or similar. Relays are usually square or rectangular components with multiple terminals.
* Inspect the fuses: Check for blown fuses (broken filaments). Replace any blown fuses with fuses of the *exact same amperage*. Don't go higher!
* Test the relays (if applicable): This is a bit more involved. You can test relays with a multimeter or simply swap the fan relay with a known good relay of the same type from another system (if possible and safe to do so) to see if the fan starts.
2. Check the coolant temperature sensor (CTS):
* The CTS tells the PCM (Powertrain Control Module) when the engine is overheating. A faulty CTS might not send the signal to turn on the fans.
* Visual inspection: Look for obvious damage to the sensor.
* Testing: You'll need a multimeter to test the CTS's resistance at different temperatures (consult a repair manual for specific resistance values). A faulty CTS often requires replacement.
3. Check the radiator fan motor(s):
* Direct power test (Caution!): This should be done *only after* you've ruled out fuse, relay, and sensor problems. Disconnect the fan's electrical connector. With the ignition OFF, directly connect the power wires to a 12V battery using jumper cables (using appropriate gauge). *Observe all safety precautions while handling batteries and electrical components*. If the fan runs, the problem lies with the wiring, relay, sensor, or PCM. If the fan doesn't run, the fan motor itself is likely faulty.
4. Check the wiring and connectors:
* Visual inspection: Carefully inspect all wiring related to the radiator fans for any damage, corrosion, loose connections, or broken wires. Repair or replace as needed. Pay close attention to the connector to the fan motor itself.
* Continuity test: You can use a multimeter to check for continuity (electrical connection) in the wiring.
5. Check the PCM (Powertrain Control Module):
* This is the last resort. A faulty PCM can prevent the fans from turning on. This is usually a more expensive and involved repair, often requiring professional diagnosis and replacement.
Important Considerations:
* Dual Fans: Many Lumina models have two radiator fans. One might be working while the other isn't. Check both.
* Low Coolant: Ensure your coolant level is sufficient. Low coolant can trigger overheating, but the fans won't necessarily run if the sensor isn't detecting the problem (due to other underlying issues).
* Repair Manual: A repair manual specific to your 1998 Chevy Lumina will be incredibly helpful throughout this process. It will provide diagrams, specifications, and troubleshooting steps.
If you're not comfortable working with car electrical systems, it's best to take your Lumina to a qualified mechanic. Attempting repairs without proper knowledge can lead to further damage or injury.
