Radiator Cooling Fan Won't Turn On
A fan that never spins lets the engine overheat in stop-and-go traffic. The good news: it's usually the fan motor, a relay, or a temperature sensor.
Severity: High
What to Do Right Now
Turn the AC on with the engine idling — the fan should kick on within a minute. If it doesn't, start with the relay (cheapest), then sensor, then motor.
Common Causes
- Burnt fan motor: Bench-test by jumping 12V to the motor. No spin = bad motor, replace the fan assembly. Shop cooling fan
- Failed fan relay: Relays click when energized. Pull the relay, swap with an identical one (often the horn relay), and see if the fan kicks on. Shop fan relay
- Bad coolant temperature sensor: The ECU uses this sensor to decide when to run the fan. A failed sensor never sends the 'hot' signal. Shop coolant temperature sensor
- Blown fan fuse: Check the under-hood fuse box for a 30–40A fan fuse. Replace with the same rating. Shop fuse
- Damaged wiring or connector: Heat near the radiator melts connectors. Inspect the harness for crispy plastic or green corrosion. Shop wiring connector