Your Volkswagen fan is supposed to turn on and off as the heating and cooling cycles start and stop. If your Volkswagen fan keeps running continuously, it indicates an issue with your vehicle’s system.
Volkswagen Fan Keeps Running – Why?
Volkswagen fan keeps running because of a dirty radiator, faulty electronic control unit, defective temperature sensors, bad fan relay, short circuit to mass wires and faulty freon pressure.
Dirty radiator
If you don’t change the coolant inside your Volkswagen as regularly as you’re supposed to, it will load the radiator with debris and even crack it.
When the central radiator or the air conditioning radiator is dirty, it will cause the engine to overheat. Consequently, this will have the Volkswagen fan running even when the engine is off.
A faulty Electronic Control Unit (ECU)
The ECU is responsible for telling the fan to switch on or off. It tells the fan to continue running, especially if the coolant system is still hot. However, if the ECU is faulty because of malfunctioning in its software, it won’t be able to tell the Volkswagen fan when to switch on or off.
This means that the fan may continue to run even after turning off the ignition. The best way to fix such a problem is to have your vehicle checked by an experienced certified mechanic.
Faulty temperature sensors
Your Volkswagen’s coolant fans operate based on the readings they get from the temperature sensors. But, if the temperature sensors are faulty or damaged, they’ll likely send the wrong readings to the ECU unit.
This reading forces the computer to switch the vehicle’s engine into emergency mode and have the fan constantly running to cool the overheating engine. This will make it difficult for your Volkswagen engine to start when it’s not heated enough.
Faulty fan relay
Most Volkswagen cooling fans usually use electric cooling fans powered by electric motors. These motors have moderate to high current draw, which explains why they’re controlled using relays. If everything is functioning correctly, the ECU unit will activate the relay and power the fans.
Your vehicle’s fan usually comprises a positive from the relay and a negative from the ECU unit. The positive from the relay is supplied consistently. At the same time, the negative from the ECU unit is only powered once the relay detects that the Volkswagen’s temperature is approaching very high temperatures.
If the fan relay is faulty, it will likely give incorrect readings to the ECU, which will force the coolant fans to stay on at all times.
Depending on the wiring setup of your Volkswagen, the coolant fans may keep running even when the ignition is off. If the coolant fan runs for a long time, it will likely drain your vehicle’s battery.
Since the fan relay is a crucial component of your vehicle’s cooling system, vehicle owners should take it very seriously. If you suspect that the fan relay is malfunctioning or faulty, you should have your vehicle checked by a professional mechanic.
Low efficiency of the cooling system
A low efficient cooling system can result from insufficient water, coolant leakage, pump failure, late ignition timing, expansion tank, or a failing thermostat. Even though this issue won’t force the Volkswagen fan to run continuously, it will turn on and off over long distances.
Short circuit to mass wires
If your car experiences a short circuit, it will affect the flow of electricity. A Volkswagen fan will most likely continue running if the circuit’s negative wire is worn-out or damaged. Based on your vehicle’s engine, you may locate positive and negative wires in different places.
However, if your vehicle has two temperature sensors, it means that once the negative wire is broken, it will force the fan to run continuously when the ignition is on.
On the other hand, if the wires of the second temperature sensor are frayed or damaged, the fan will continue running even when the ignition is off.
Faulty Freon pressure sensor
If the Freon pressure sensor is faulty and causes the refrigerant to leak, the coolant system will detect the radiator is overheating and turn on the fan to cool it. In fact, for some Volkswagen vehicles, the fan will continue running, especially if the air conditioning is on.
This shouldn’t be happening since it shows a problem with the Freon pressure sensor or the radiator is clogged.
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Does the Volkswagen Fan Keep Running After Shutting The Engine Off?
If your car has been running for a while, shutting the engine off won’t magically cool it down. If the water’s temperature exceeds the recommended threshold, the Volkswagen fan will likely continue running to cool it off even when the engine is off.
This is normal as the engine’s temperature can sometimes increase since the coolant is no longer circulating. Therefore, the fan needs to continue running until the coolant’s temperature drops and the engine cools entirely.
How Long Should VW Fan Run? When Should It Be Turned Off?
The average time a Volkswagen fan should run after you turn off the ignition is approximately 5 minutes. However, this time varies depending on the vehicle’s model and how long it has been driven. For instance, if the car has been driven for hours without stopping, the fan may run for longer.
The fan’s primary purpose is to get rid of heat and cool down the engine. Therefore, it’s okay for it to run for a few more minutes even after turning off the engine. For most Volkswagens, the fan is supposed to run 2-5 minutes after the ignition has been turned off.
If the fan runs past five minutes, it indicates a problem with your vehicle’s system. For instance, if your Volkswagen fan runs for more than 30 minutes, it may be best to turn it off. You can do this by disconnecting the battery’s negative terminal. It will help prevent the vehicle’s battery from draining out.
Troubleshooting Tips For Volkswagen Fan Problems
If your Volkswagen fan runs for a very long time after you turn off the ignition, there are several diagnostic steps you may attempt to assess the root of the problem and fix it.
- You can start by testing the fan relay for any issues. If you’re sure that the fan is running continuously due to a faulty relay, you should replace the bad relay with a new one. However, ensure that the new fan relay has the same pin design as the old one.
- Use a stick to measure the coolant levels and if there are any possible leaks. If the coolant levels are low or have visible leakages, the Volkswagen fan will continue running even if the ignition is off.
- If the radiator is covered with dirt and debris, ensure that you clean it. Since the radiator can easily clog from the inside, you should leave the work to a professional mechanic. They will likely dismantle the entire radiator and clean it using a special solution.
- Check the ECU for any errors. You can do this using a diagnostic scan tool to read and fix the errors.
- Use a digital multimeter to check for any frayed or damaged wires.
- Check the coolant temperature sensor for any faults. If the sensor isn’t functioning correctly, it may be best to replace it with a new one, and the fan will stop running continuously.