Is your Ford Fusion’s radiator fan staying on even after the engine cools off? The frustration of a radiator fan running constantly can be all too familiar for Ford Fusion owners. Just like any vehicle, the Ford Fusion can encounter its fair share of common problems, and its radiator fan is no exception. From a fan relay stuck in the ON position to low antifreeze levels, there are various reasons why the radiator fan won’t turn off.

This blog will serve as a helpful guide for troubleshooting and resolving this perplexing problem. Whether it’s a simple fix like replacing fan relays and topping up antifreeze or a more complex solution like replacing temperature sensors, the blog covers all the bases.

Troubleshooting Ford Fusion Radiator Fan Runs Constantly: Common Issues and Solutions

Ford Fusion owners might notice that even after the engine cools down, the radiator fan continues to run, which can be a cause for concern. The fan should turn off once the engine reaches a certain temperature, but when it remains operational, it could indicate an underlying problem that needs attention. Let’s explore some of the possible cause of this issue:

Ford Fusion Fan Relay Stuck in the ON Position

One of the potential reasons for the radiator fan running constantly is a malfunctioning fan relay that gets stuck in the ON position. The fan relay is responsible for controlling the operation of the radiator fan based on the engine temperature. When the relay fails or gets stuck in the ON position, it continuously supplies power to the fan, causing it to run even when the engine has cooled down.


To troubleshoot this problem, start by locating the radiator fan relays in Ford Fusion, as there may be multiple relays associated with the fan. Carefully remove each relay one by one to identify the faulty one. Once you’ve identified the faulty relay, replace it with a new relay that is suitable for specific Ford Fusion variant, to restore proper fan operation and prevent unnecessary fan running.

Low Antifreeze Levels

Insufficient antifreeze or coolant levels in the cooling system can lead to inadequate engine cooling, preventing the temperature from reaching the required threshold to turn off the radiator fan. This issue can arise due to leaks in the cooling system or inadequate maintenance practices.


To address this, it’s crucial to regularly check and top up the suitable antifreeze for your Ford Fusion to the appropriate level. By maintaining the correct antifreeze level, you can ensure the cooling system functions effectively, allowing the engine to cool down properly and preventing the radiator fan from running excessively.

Air Trapped in the Coolant System

Air trapped in the coolant system can disrupt the circulation of coolant, affecting the cooling performance of the engine. This trapped air can cause hot spots, leading the temperature sensor to believe that the engine still requires cooling, keeping the radiator fan active.


To address this issue, bleeding the air from the coolant system is necessary. This process involves releasing the trapped air and ensuring that the coolant flows smoothly throughout the system, helping the fan operate as intended.

Malfunctioning Temperature Sensor

The temperature sensor in the Ford Fusion plays a crucial role in monitoring the engine temperature and signaling the fan when to turn on and off. If the temperature sensor malfunctions or provides inaccurate readings, it can lead to improper fan operation. For instance, if the sensor fails to detect that the engine has cooled down, it will keep sending a signal to keep the fan running.


Replacing the faulty temperature sensor with a new and functioning one can rectify this issue and restore the fan’s proper functioning.

Malfunctioning Ford Fusion AC

Another reason why the radiator fan in the Ford Fusion may spin at high speed, even in normal ambient temperatures, is when the A/C system is turned on.

The A/C system is closely monitored by the PCM , which communicates with the HVAC module over the truck network to operate the system. If the PCM detects high pressure in the A/C system, typically caused by excess heat, it commands the cooling fans to run at high speed to reduce the A/C system pressure by dissipating heat from the condenser.

There may be several potential causes for the problem:

  • Faulty A/C pressure switch.
  • Faulty Thermal Expansion Valve
  • Faulty A/C Compressor
  • Evaporator Leaked Out all the Freon


In conclusion, the radiator fan running constantly or spinning at high speed in the Ford Fusion can be a serious issue that may disrupt the normal functioning of the vehicle. However, by understanding the potential reasons behind this problem and following the troubleshooting steps discussed in this blog, Ford Fusion owners can effectively address and resolve the issue. Whether it’s a malfunctioning fan relay, low antifreeze levels, or problems with the A/C system, taking appropriate actions such as replacing faulty relays, topping up antifreeze, or addressing A/C system components will ensure proper fan operation and prevent unnecessary fan running.

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