Fan Noise After Turning Engine Off: Here’s Why And How To Fix

In-Depth Troubleshooting: Fan Noise After Turning Engine Off

Once you have confirmed it’s not the usual 30 seconds to 5 minutes of fan noise, it’s time to troubleshoot the problem. Let’s check out the roots of the problem and how you can deal with it.

Faulty Thermostatic Switch

The switch activates the fan relay when the engine reaches a particular temperature and then turns on the fan to cool it down. However, a malfunctioning switch falsely signals the fan relay to turn on.

It even does that when it is not necessary since it is unable to measure the engine temperature accurately. Consequently, even after the engine has been turned off, the cooling fan keeps running.

Fix

You need to inspect the thermostatic switch for damage and replace it if damaged. Here’s how you can do that;

• Locate the thermostatic switch commonly located near the radiator or on the engine block.
• Inspect it for any signs of physical damage, such as cracks or corrosion.
• Confirm its functionality using a multimeter. You can do that by connecting the multimeter’s probes to the switch’s terminals in continuity mode.
• Once confirmed, it’s a faulty piece, disconnecting the negative terminal of the vehicle’s battery.
• Disconnect the electrical connector from the thermostatic switch and take it out.
• Replace it with a new one and re-do the steps backward.

Here’s a video that will help you use a multimeter properly;

Malfunctioning Time Relay

If your vehicle is equipped with a time relay, then a faulty time relay may be the reason. The time is predetermined by the manufacturer, and if the relay malfunctions, then the fan may run continuously.

On the other hand, there is also a chance that the relay is fine but there are loose connections or corroded connections present.

Fix

Here’s how you can do your inspection and fix it;

• Locate the time relay, which is generally located near the radiator.
• Check the continuity of the relay by measuring the resistance using a multimeter.
• Replace the timer relay with a new one if found faulty.
• If the relay is fine then check for loose connections and corroded connections around the fan motor, control module, and temperature sensor.
• Once any loose or corroded connections are located, tighten or replace them respectively.

Cooling System Malfunction

The issue could be with the cooling system overall, which is a key factor in determining how long the fan should be on. However, the main problems found within the cooling system are a low coolant level and the radiator or hoses being blocked.

Thus, even after the engine is switched off, the fan might not stop, and the fan could constantly run, leading to noise issues.

Fix

Here’s how you can fix a cooling system malfunction;

• Locate the coolant reservoir near the radiator, which is marked with a cap that says “coolant” to check the coolant level.
• Refill the coolant if low.
• Check out the radiator and hoses for blockage.
• Simply clean any dirt and debris that is present by connecting a garden hose to the radiator or hose. Later on, run the water through the system.

Broken Or Dirty Cooling Fan

If the cooling fans are broken or dislocated, they cannot dissipate the heat effectively as before. Thus, it may take more time to provide the same level of cooling to the engine.

On the other hand, the same goes for dirty cooling fans as well. A dirty one is never able to release the heat.

Fix

The fix is quite simple. Here’s how you do it;

• Locate the cooling fan near the radiator at the front of the engine compartment.
• Check for any dirt and debris.
• Use a soft brush or compressed air to gently remove any loose debris from the surface of the cooling fan blades.
• Take some mild detergent and water into a spray bottle and make a mixture of it.
• Spray some solutions onto the fans and wait a few minutes to loosen the stuck dirt.
• Use a soft brush or toothbrush to scrub the fans gently.
• If the cooling fan is dislocated or broken, you need to remove it and replace it with a new one.