Experiencing a situation where the radiator fan of your 2015 GMC Sierra won't turn off can be quite frustrating. This issue is often linked to problems with the cooling system, particularly with the coolant temperature sensor or thermostat. Understanding the symptoms, causes, and solutions can help you address the problem effectively.

Symptoms of the Issue

When your GMC Sierra's radiator fan continues to run after the engine is turned off, you may notice:

  • The temperature gauge remains low (around 160°F) even after driving.
  • The fan runs continuously or at high speed for several minutes post shutdown.
  • Air conditioning may not function properly.

These symptoms indicate that the cooling system is not operating correctly, often due to faulty components.

Common Causes

The primary reasons for the radiator fan not turning off include:

  • Faulty Coolant Temperature Sensor: If this sensor is malfunctioning, it may incorrectly signal that the engine is overheating, causing the fan to run continuously.

  • Stuck Open Thermostat: A thermostat that fails to close can prevent the engine from reaching its optimal operating temperature, leading to persistent fan operation.

  • Electrical Issues: Problems such as a short circuit or a glitch in the vehicle's computer system can also cause the fan to remain on.

Solutions

To resolve this issue, consider the following steps:

  • Check and Replace the Coolant Temperature Sensor: If you suspect this part is faulty, replacing it is a straightforward process. Make sure to disconnect the battery before beginning any repairs.

  • Inspect and Replace the Thermostat: If replacing the sensor does not resolve the issue, check the thermostat. A stuck open thermostat will need to be replaced to restore proper temperature regulation.

  • Resetting the System: After replacing either component, it's advisable to reset your vehicle's computer by disconnecting the battery for a few minutes. This helps ensure that any previous error codes are cleared and that the system recalibrates to recognize new parts.

  • Temporary Measures: If immediate repair isn't possible, you can temporarily unplug one of the fan fuses to stop it from running. However, this should only be a short-term solution as it may lead to overheating if not addressed properly.

Conclusion

Addressing a radiator fan that won't turn off in your 2015 GMC Sierra typically involves checking and possibly replacing either the coolant temperature sensor or thermostat. By understanding these components and their functions within your vehicle's cooling system, you can take effective steps toward resolving this issue. Always consult a professional mechanic if you're unsure about performing these repairs yourself.

FAQs About GMC Sierra Fan Issues

    • What should I do if my radiator fan keeps running?
      Check for faulty coolant temperature sensors or thermostats as these are common culprits.
    • Can I drive my truck if the fan won't turn off?
      It's best to avoid long drives until you resolve this issue as it could lead to overheating.
    • How can I reset my truck's computer?
      Disconnecting the battery for a few minutes will reset your vehicle's computer.