Radiator fans are designed to turn on when the temperature in your car’s engine reaches a certain level (around 200°F). So what will happen if your radiator fan runs constantly even when the car engine is off? Read the article and you will find some reasons and how to fix this problem.
When is Your Radiator Fan Supposed to Start?
The car radiator fan functions to coordinate with the coolant to help cool your engine during operation. Although it is only a small part, thanks to this, the car engine runs more efficiently and stably. The cooling fan is activated in 2 ways:
Method 1: Using a thermostat: The thermostat is located between the engine and the radiator to help control the temperature. When the coolant temperature reaches a certain threshold and the engine is running at full capacity, the radiator fan starts.
Method 2: Using the electrical system: When the engine coolant starts to heat up, the electric relay switch is activated, which causes the cooling fan to operate.
Simply put: The engine temperature will activate the radiator fan to start. And your fan will turn off once the engine cools below 200 degrees. When your coolant reaches about 200-230 degrees, the radiator fan starts. Normally, it takes 15 to 20 minutes for the radiator fan to turn on after the control valve is turned off.
Why My Radiator Fan Runs Constantly.
Are you probably concerned about the reason why my radiator fan keeps running? There are many things that can happen to your engine fan. It could be a blown fuse and it will be cheap and easy to fix when the radiator fan has problems with this issue. But more difficult and complicated in the situation where the temperature sensor broke, causing your fan to turn on too early and not stop running. To learn more about the reasons for the scenario, keep reading:
Faulty Temperature Sensor
The cause of the radiator fan running continuously can come from the temperature probe, which is the part that determines when the radiator fan should operate. The coolant temperature sensor is a thermistor and its resistance changes when the coolant temperature changes. When the resistance changes, the signal is sent to the ECU and it will determine when to activate the radiator cooling fan when a certain temperature is reached. And when the temperature sensor was not working properly, the consequence is that the signal to send to the computer is wrong and makes your coolant keep running. This problem can be solved by finding the location of the temperature sensor, trying to disconnect the wire, or connecting to another sensor.
Stuck Fan Relay
An important reason we cannot help but mention is that your car had a problem with the cooling fan radiator. Consider the cooling fan relay as the main display that controls the operation of the cooling fan. If this part does not work, nothing prevents the fan from starting when the engine temperature drops to the required threshold. To know the exact level of relay damage, you can use the VOM meter to measure the relay voltage. If the meter is only 12V, it is normal, otherwise, the relay is damaged and needs to be replaced. Identify the relay location in the fuse box, then remove the problematic relay.
Faulty Fan Switch
You have probably heard of a component called a cooling fan switch. This system is connected to the thermostat and works exactly like your home’s HVAC system. If any of these components fail, your radiator fan turns on permanently, leading to serious problems. The function of a fan switch is similar to the work of the coolant temperature sensor. This means that when a certain temperature is reached, the fan switch will send the signal to the computer and activate the cooling fan.
Having Problems with the ECU Unit
The ECU unit performs the task of processing data and controlling the activities taking place inside the motor vehicle. When this part has a problem, the vehicle’s operation will be immediately interrupted. Typically, the ECU will send the signal to the fan to start if the cooling system is still hot. The ECU tells the fan when to turn it on or off. When a faulty ECU, it cannot tell the cooling fan when to turn off.
Short Circuit in Electrical Wires
If you check that the engine has cooled down and the radiator fan is still running, the negative wire is probably damaged. If the engine design provides for two coolant temperature sensors, then if the “minus” sign of the first sensor fails, the fan will run on ignition. In case of insulation failure of the wires of the second water temperature probe, the fan runs continuously while the engine is running. At this time, the vehicle user must disconnect the two poles of the wire and check the current operation through the voltmeter. If no power passes, the wire is damaged. Furthermore, this method also helps users locate the fan relay on the hood. Check the current from the relay to the fan, if power appears there, it means the car’s cooling fan has a problem.
Damaged Fan Clutch
The fan clutch serves to attach the radiator fan to the engine system and to rotate the engine. The fan will not work properly if the clutch goes bad. Wear after a long period of use causes the clutch spring to corrode. When the springs are corroded, it will interrupt the engine’s movement and may prevent your car from running.
What Happens if a Radiator Fan Keeps Running When the Car is Off?
The answer depends on how long your radiator fan runs. It will be a normal situation if after running your engine, the water in the radiator is hot and needs to be cooled. Once you turn off the engine, the car’s computer detects that the radiator is at a higher temperature and still needs to dissipate heat. But if your radiator fan usually stays on for more than 2 minutes, contact the repair service. There is probably a part that can go wrong.
If the fan runs for a long time, the fan can be damaged due to excessive use. The purpose of designing this part is only to turn it on and off when necessary and if the radiator fan runs continuously, it will shorten the lifespan of this component, and more seriously, it can cause your battery to drain and prevent your car from starting. On the market, most modern car fans have a module that tells you when to turn them on and off. Perhaps you have a faulty module or relay in your car.
How to Prevent Your Radiator Fan from Running Constantly?
The cooling process of cars plays a very important role, just like engine lubrication. Therefore, in addition to paying attention to monitoring and periodically changing the car’s oil. You should also regularly check the radiator fan control system to ensure that this part is still working well. Below are instructions on how to check the basic radiator fan to help limit the condition of the fan running continuously:
Inspect and Clean the Radiator Fan
Drivers should test the fan by opening the car hood, starting the engine, and setting the air conditioner to the highest temperature. At the same time, you need to monitor the temperature gauge to ensure that the overheating engine does not overheat.
If your radiator, both the main radiator and the air conditioning radiator, is covered with dirt, the heat exchange process will be disrupted. Therefore, the fan must run almost continuously to cool the system. Cleaning the fan is a very important step. You can use degreaser to remove all the dirt on the fan housing as well as on the blades.
Fan Wiring and Power Supply
After cleaning every space of your radiator fan, please check the wiring and power supply. These are two types of positive and negative wires that power the fan. Drivers must disconnect the fan cable and check that the connector is not damaged, corroded, or poorly connected.
Check the Car Coolant
One of the simplest ways to ensure your fan is not damaged is to inspect your coolant. This is very easy to do to ensure your engine is running at the optimal temperature. Just open the hood and check the coolant level. It has min and max markers on it. The standard fluid level to help your fan function properly should be between these two levels.
When all parts show no abnormal signs, remember to diagnose the ECU unit. If this happens to your car, disassembling and dismantling the ECU is the necessary step. After that, you need to inspect the internal board inside the ECU and you can even clean the oxides with alcohol.
Final Thoughts: Why Does My Cooling Fan Keep Running?
For the radiator to cool the car system. A large amount of air is needed to pass through the aluminum fins. The radiator fan creates the necessary airflow and increases air circulation at the radiator inlet, thus helping to cool the engine more efficiently. When the cooling fan runs constantly, it will affect your engine’s performance. And more serious consequences can occur, so it is necessary to detect this problem in time. However, there are many reasons causing this phenomenon that sometimes make it difficult to diagnose the exact cause. Through our article, we hope it will partly help in dealing with this problem.