BMW 318is Radiator Fan Isn't Working

Diagnosing the Causes of a Non-Functional Radiator Fan in Your BMW 318is and How to Fix It

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Reviewed by
Aisha
Written by RepairPal Car Genius
Updated January 14, 2025
0%
34% chance it's the
Fan Motor or Clutch
0%
28% chance it's the
Fan Relay or Fuse
0%
23% chance it's the
Temp Sensor or Fan Control Module
0%
15% chance it's
Something else
The most common reasons a BMW 318is radiator fan isn't working are the fan assembly, the fan clutch, or the coolant temperature sensor.
  • Fan Motor or Clutch: A faulty fan motor or a malfunctioning fan clutch can result in inadequate cooling, causing the engine to overheat.
  • Fan Relay or Fuse: A faulty fan relay or blown fuse can prevent the cooling fan from operating, leading to engine overheating.
  • Temp Sensor or Fan Control Module: A faulty temperature sensor or fan control module can result in incorrect readings, causing the engine to overheat or the cooling fan to operate improperly.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a BMW 318is radiator fan isn't working?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

Over time serpentine belts stretch, crack, and the ribs that ride on the accessory pulleys being to wear smooth. A squealing noise that increases with engine speed or as engine driven accessories are turned on may be noted. The noise is caused by the belt slipping on the pulleys, insufficiently driving them. Ineffective air conditioning, a battery warning light, or intermittent power steering assist can result from this.

»MORE: Symptoms of a bad serpentine belt

The first indication of a defective fan clutch is a healthy cooling system that runs below or above the normal temperature range. This is due to the fan running too fast or too slow. Also, a seized cooling fan will cause a loud roaring fan noise from under the hood every time the accelerator is pressed, and the engine will feel as if it lacks power. In this situation it would be very difficult to turn the engine cooling fan by hand, of course when the vehicle is off. Finally, if the clutch fails the fan will either turn very slowly, and not respond well to engine speed.

The bad thermostat can cause two different sets of problems, depending on whether it's stuck open or stuck closed.

A thermostat that is stuck open can cause the engine to run colder than normal and turn on the check engine light. It may also cause poor fuel mileage and the heater to blow cool air.

A thermostat that is stuck closed will cause the vehicle to overheat. If a new thermostat doesn't resolve engine temperature problems, the cooling system needs to be checked for other issues.

» LEARN MORE: Signs of a bad thermostat, and how to fix it

When the engine coolant temperature sensor fails, it will send inaccurate information to the vehicle’s computer, causing the computer to react to false operating conditions. This will cause the engine to consume more fuel than normal, depleting fuel mileage, and causing black, sooty smoke from the engine under moderate to heavy acceleration. The check engine light will illuminate, and on-board diagnostic trouble codes may be stored for exhaust and emission system failure, fuel delivery system failure, and engine cooling system failure. Overheating may also occur, as the coolant sensor may be leaking fluid out of the engine, creating a an air pocket in the system.

Troubleshooting Radiator Fan Issues in a BMW 318is

When troubleshooting radiator fan issues in your BMW 318is, begin by identifying which fan is malfunctioning, as there are typically two: the auxiliary fan and the primary fan located between the radiator and engine block. Start with basic tests, such as removing the radiator temperature switch to see if this affects the fan's operation, which can help you determine if the fan itself is functional. Next, check the temperature switches that control the fan's activation based on coolant temperature; these are crucial for proper fan operation. Consulting the Bentley BMW series manual for E36 models can provide valuable insights into the expected fan behavior at various temperatures. If the fan is still not operating correctly, inspect the electrical components, including the coolant temperature sensor, fan relay, and wiring, as faults in these areas can disrupt fan functionality. Additionally, consider the lifespan of the fan motor itself; if it shows signs of wear or malfunction, servicing or replacement may be necessary. Lastly, if you notice the fan running continuously, investigate the cooling fan relay and potential internal shorts, as these issues can lead to battery drainage. By following this structured approach, you can effectively diagnose and resolve radiator fan issues, ensuring your BMW 318is maintains optimal cooling performance.

How to Diagnose a Non-Working Radiator Fan in a BMW 318is?

When diagnosing a non-working radiator fan in a BMW 318is, it's crucial to recognize the common problems that may be affecting the fan system. A frequently encountered issue is a malfunctioning fan motor, which can fail due to wear and tear or electrical faults, preventing it from spinning. The fan clutch is another component that can cause problems; if it doesn't engage properly, the fan won't operate as intended. Additionally, electrical issues such as a faulty fan relay or blown fuses can interrupt the power supply, leading to fan failure. Temperature sensors that provide inaccurate readings can also mislead the system, resulting in the fan not activating when necessary. Lastly, problems with the fan control module can disrupt the fan's operation altogether. By understanding these common failure modes, you can methodically inspect each part, ensuring a comprehensive diagnosis and effective repair of the radiator fan issue in your BMW 318is.

Why is the Radiator Fan Not Working in a BMW 318is?

When the radiator fan in your BMW 318is fails to operate, it is crucial to address the issue promptly to avoid severe engine damage or overheating. A malfunctioning fan can lead to inadequate cooling, which may result in the engine reaching dangerously high temperatures, potentially causing a complete breakdown or costly repairs. Common causes of fan failure include a faulty fan motor, a defective coolant temperature sensor, or issues with the fan relay or fuse. Additionally, if your model lacks an auxiliary fan or has a malfunctioning fan clutch, these can exacerbate cooling problems. The radiator fan is designed to activate when the coolant reaches a specific temperature, and if it does not, the engine's performance and longevity are at risk. Therefore, diagnosing the exact cause of the fan's malfunction is essential for maintaining your vehicle's cooling system and ensuring safe operation on the road. Ignoring these symptoms can lead to significant safety risks and expensive repairs, making it imperative to take action as soon as you notice any signs of trouble.

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