EVIL ENERGY 8/10/12/14/16 Inch Electric Radiator Cooling Fan - Compatible with Automobile Radiators

Q: How to test a radiator fan?

A: Let the engine cool, switch off the ignition, and keep hands and tools away from the blades. An electric radiator fan can start unexpectedly when the engine compartment is hot.

Use this diagnostic sequence:

1. Inspect the blades for obstruction or damage. Check the fuse, radiator cooling fan relay, connector, wiring, and chassis ground.
2. With a cold engine, compare the scan-tool coolant-temperature reading with ambient temperature. A clearly unrealistic reading may indicate a sensor or wiring fault.
3. Start the engine and monitor coolant temperature. If the vehicle supports it, command the fan on with a bidirectional scan tool. Switching on the A/C is a useful screening test on many vehicles, but it does not activate the fan on every model.
4. When the fan is commanded on, measure voltage across the fan connector. Battery voltage with no fan movement suggests a failed motor, blocked blade, or poor connection. No voltage indicates a fuse, relay, wiring, sensor, or controller problem.
5. Use a fused battery test only after disconnecting the fan from the vehicle harness.

For a radiator fan not working, test the motor and control circuit separately before replacing parts. Ford also warns that a cooling fan may continue operating after the engine stops, so physical inspection must be performed cautiously. 

Q: How much is a car radiator fan?

A: A universal 12V aftermarket fan generally costs about $40–$100 for the fan alone. Current retail examples include 10- and 12-inch universal fans priced from approximately $39.99 to $63.99. A complete package with a temperature-controlled wiring harness and relay can cost more than $100; for example, one comparable 10-inch fan-and-controller kit is currently listed at $112.08. 

A vehicle-specific radiator fan assembly can cost considerably more because it may include a shroud, multiple fans, resistor, or electronic control module. Current retail examples range from about $129 to more than $400 for the part alone. RepairPal’s national estimate for complete fan-assembly replacement averages $1,176–$1,306, including approximately $280–$411 in labor, although the cost varies substantially by vehicle and location. 

EVIL ENERGY offers a more complete option for custom or universal installations. The current 8-inch single-fan kit starts at $55.99, while the 12-inch single-fan variant is $64.99. Instead of supplying only the electric radiator fan, the kit includes mounting hardware, wiring components, circuit protection, and a 175–185°F thermostat relay switch for automatic operation. Buyers can choose 8-, 10-, 12-, 14-, or 16-inch sizes and single- or dual-fan packages, reducing the need to purchase control and mounting parts separately.

Q: How to connect a 12 volt radiator fan directly to a battery?

A: A direct battery connection should only be used as a brief motor test. It is not suitable as permanent wiring because the fan would have no automatic temperature control.

1. Secure the fan so it cannot move when the motor starts.
2. Disconnect it from the vehicle wiring harness.
3. Use jumper wires of adequate gauge with an in-line fuse on the positive lead. The EVIL ENERGY kit provides 30-amp circuit protection; follow the supplied diagram for the exact components.
4. Connect the fused positive lead to the fan’s positive terminal and the negative lead to battery negative or a clean chassis ground.
5. The fan should start immediately. Stop the test if the wires become warm, the fuse opens, or the fan fails to rotate freely.

A permanent 12 volt automotive fan installation should use a fuse, relay, temperature switch, and secure ground. Do not route full motor current through a small dashboard switch. This also applies to a 12 volt electric fan for cars used as an auxiliary fan. Official electric-fan installation instructions likewise specify fused power, relay control, suitable wire gauge, and a metal-to-metal chassis ground. 

Q: How to make a radiator cooling fan turn on automatically?

A: Use a thermostat switch, correctly rated radiator cooling fan relay, fuse, and suitable wiring. The temperature switch should control the relay coil rather than carry the fan motor’s full current. The relay then supplies battery power to the fan when the switching temperature is reached.

The EVIL ENERGY 12 volt radiator cooling fan kit includes a thermostat relay switch with a stated 175–185°F operating range. Follow the supplied wiring diagram and wire colors because relay-terminal arrangements can differ between harnesses.

If the auto radiator fan does not start:

• Confirm battery power and fuse continuity.
• Check the ignition-switched control supply.
• Verify that the temperature switch is installed in the coolant path.
• If the switch grounds through its threads, confirm that sealant has not insulated the electrical ground.
• Check whether the relay clicks when the control circuit is activated.
• If the relay clicks but the fan remains off, test the relay output, fan wiring, motor ground, and motor.

Do not deliberately overheat the engine to trigger the fan. Use an appropriate scan tool or safely test the control input according to the wiring instructions. 

Q: How to replace a radiator fan?

A: First determine whether the vehicle uses a simple two-wire motor, a relay-controlled multi-speed system, or a PWM fan with an integrated control module. A universal two-wire fan should not automatically be connected to an OEM electronic fan-module output.

For a typical replacement:

1. Allow the engine to cool and disconnect the negative battery terminal.
2. Unplug the fan and remove the shroud or mounting hardware without damaging the radiator fins.
3. Compare the replacement fan’s dimensions, mounting depth, airflow, current draw, and pusher/puller direction with the original installation.
4. Mount the fan securely and confirm that the blades clear the radiator, hoses, wiring, and engine accessories.
5. Install the correct fuse, relay, temperature switch, and ground.
6. Reconnect the battery and verify fan operation through a complete temperature cycle.

If the installation requires removing a threaded coolant sensor, follow the vehicle manufacturer’s coolant-draining and air-bleeding procedure. When selecting a high CFM radiator fan, confirm that the alternator, wiring, fuse, and relay can support its current draw. Many aftermarket radiator electric fans cannot be selected safely by diameter alone.

Q: Why does my radiator fan stay on?

A: A fan running briefly after shutdown can be normal when the engine compartment is hot. Some factory systems intentionally continue cooling after the engine stops.

For an aftermarket radiator fan not turning off, common causes include:

• The thermostat circuit was connected to constant battery power instead of ignition-switched power.
• The relay contacts are stuck or welded closed.
• The temperature-switch wire is shorted to ground.
• The thermostat switch remains closed.
• An A/C or manual-override input remains active.
• Coolant temperature is genuinely still above the switch-off point.

Allow the engine to cool before diagnosing it. Disconnect the thermostat control wire according to the wiring diagram: if the fan stops, investigate the sensor, control wire, or switched-power connection; if it continues, inspect the relay contacts and high-current wiring.

On an OEM system, continuous operation can also be a fail-safe response to an implausible coolant- or cylinder-head-temperature signal. An Audi technical bulletin, for example, documents permanent fan operation together with temperature-sensor and cooling-system fault codes. Scan for diagnostic trouble codes before replacing the motor.