It’s always troublesome when your engine begins to overheat. That’s precisely why the Radiator Fan exists, to cool down your powerful engine from overheating and getting damaged over the years. But sometimes things get different when your radiator fan only turns on when AC is on.
That’s why your Radiator Fan is also called a cooling fan, and it’s especially useful when the car is idling, or when you’re driving at really slow speeds (maybe inching through traffic).
However, if you’ve noticed that the Radiator Fan does indeed work, but only when you’ve switched on your AC then we’ve got a unique problem on our hands. It can be quite troublesome as well, you don’t want to be forced to switch on the AC just so that the radiator fan begins to work. Furthermore, switching on the AC all the time can unnecessarily use up gas, especially when the car is stationary.
In an automobile, the radiator is the most crucial component. This post will explain why and how the radiator fan only turns on when the air conditioner is turned on and other 03 issues.
The radiator in your automobile is one of the most basic components in the vehicle, and it is often overlooked until a problem arises. At this point, it becomes a major headache. All it is doing is reducing the temperature of your vehicle. Its most important job, that of cooling your engine, is not performed in most cases for more than a minute. If you have a problem with your car’s radiator, one of the issues you should check is “radiator fan only turns on when the a/c is turned on.”
So, why does this happen?
Table of Contents
What Happens If the Fan in My Car Doesn’t Work? Can I Still Drive My Car?
You can still drive your automobile without using the radiator fan, but you should never do so. When it comes to engine performance and longevity, your vehicle’s cooling system is critical. The overheating of your engine causes significant harm, and you must avoid it at all costs.
You should begin troubleshooting as quickly as you believe that your radiator fan has stopped functioning or that your vehicle isn’t getting adequate cooling since this will allow you to locate the root of the issue. As soon as you find you cannot solve the problem, take your car to a technician who will also diagnose the issue for you.
When the air conditioning compressor is turned on, it is normal for the radiator fan to turn on due to the activation. In some cases, the radiator fan will require the radiator fan when the temperature sensor in the bottom tank of cooling fluid exceeds roughly 212F.
The radiator fan only turns on when the AC is switched on because there is an issue with either of these components:
- Thermostatic switch
- Fan resistor
- Temperature switch
- High/Low-speed Relay
- Other wiring issues
- Clutch for the fans
- Faulty Fuse
- Coolant issues
- Radiator Fan Motor Not Working Correctly
We’ll delve into the specifics of what could’ve gone wrong with each of these parts along with tips on how to identify and diagnose so that you know which one has gone wrong.
If your car is still not cooling down and continues to overheat even when the AC is on, you might want to check out our separate article on this issue.
Top 8 Reasons Why Radiator Fan Only Turns On When AC is On
Here are a couple of the most likely reasons why your radiator fan will not work otherwise, but only switch on once you turn on the AC. Keep in mind that we’ve written this article catered to the layman so that you can diagnose and troubleshoot on your own without having to rely solely on professional help. You’ll save more money this way. However, before you make a final call on replacing a part, it might be wise to quickly get a second opinion.
Reason #1: Faulty Thermostatic Switch
The thermostatic switch is located on the side of the electric radiator cooling fan assembly. What is supposed to happen is that as the temperatures of the car (not just inside but the unsprung weight components like the engine) begin to rise, the switch automatically flips and starts the radiator fan.
This is supposed to be a smooth mechanism and take place regardless of whether you’ve switched on your AC or not. The thermostat switch will simply detect higher temperatures and then switch on the radiator fan. It will only switch off the radiator fan once it has detected that the temperatures are no longer high, and have come back down to normal recommended levels.
However, if your thermostatic switch is no longer working, this ability of the thermostat to detect the temperature levels and automatically reduce them is no longer enabled. This means that the thermostatic switch is not doing its job. The reason why the AC is influencing the radiator fan is that the higher refrigerant pressure is activating the fan, but this is a shortcut and not the intended standard operating procedure.
However, if your thermostatic switch is no longer working, this ability of the thermostat to detect the temperature levels and automatically reduce them is no longer enabled. This means that the thermostatic switch is not doing its job. The AC influences the radiator fan because the higher refrigerant pressure activates the fan, but this is a shortcut and not the intended standard operating procedure.
Solution: We will have to determine whether your thermostat is no longer functioning, or if it is simply the switch that is not flipping when required. It’s easy to check whether your thermostat is functioning on your own. You’ll have to remove the radiator cap and allow the engine to idle to observe whether the coolant is flowing or not. And if steam is coming from radiator cap then there is a different problem . Check out this article for more information on how to check your thermostat.
Once you’ve figured out the thermostat is to blame, replacing it is the easy part. Look for replacement thermostats and install them yourself! Make sure to first check if it is compatible with your car.
Reason #2: Fan resistor not working
While it’s unlikely that your entire fan needs to be replaced, sometimes just one component isn’t working correctly. This could be the fan resistor. This resistor is an electrical component and is responsible for the radiator fan’s speed. If the fan resistor isn’t working properly, it can cause the radiator fan to malfunction in the way that you’re experiencing.
Solution: Once you confirm that the fan resistor is indeed at fault, it’s a very simple job of replacing the part. However, the first part is slightly tricky. We recommend that you undertake the consultation fee of a mechanic so that they can confirm the fan resistor is to blame, but source the replacement fan resistor yourself. It generally costs less than $20, but you can end up spending close to $150 if you do this through a local dealer or repair shop.
Reason #3: Temperature Sensor Faulty
You might be thinking that the temperature sensor and the thermostat switch are the same things. They are actually not, and both can have a major role to play in the functioning of your radiator fan. The thermostat is programmable, while the temperature sensor is also called the CTS and also controls the radiator fan but it is not programmable.
One of the main symptoms that your temperature sensor is faulty is that the engine will begin to overheat. It’s possible that the temperature sensor is constantly sending a permanent cold signal which is blocking the radiator fan from being switched on. Simply put, the sensor thinks the car is cold when it is actually hot!
Solution: You will definitely have to replace the temperature sensor, and you can do it on your own, just like the other parts on our list. Find the correct replacement temperature sensor according to your car model and make and do it yourself at home!
Check this video out for more troubleshooting help for your Radiator fan
Reason #4: Faulty Fuse
An automobile’s electrical system is supported nearly entirely by its fuse box. When an electrical surge is directed at a piece of electronic equipment, the fuse turns off the electric supply to that piece, preventing it from being destroyed by the electrical surge itself. This is referred to as a blown fuse in the electrical industry.
A blown fuse is not a major problem, and replacing one does not require a significant investment of time and resources. Identify the fuse again for the radiator fan controller or the fan if your car’s radiator fan is not functioning properly. Consult your car’s user handbook to determine which fuse to replace.
It is common for the fan to be powered by a large fuse of roughly 50A, with a smaller fuse for the fan control module. If the fan fuse blows, it is important to remember that there may be an issue with the wiring or the radiator fan.
Reason #5: Wiring Issues Are a Problem
There could be a wiring issue or a broken connection if the fan does not operate even though the car is overheated.
The wiring from the control unit or relay to the radiator fan should be double-checked. If there is any rust in the connecting plugs, replace them. Also, make sure the connecting connectors at the relay and the control unit are in good working condition.
A multimeter is not always very useful for testing wirings; you must apply a load to the wires to determine whether or not they are functioning properly. A multimeter, however, may be used to quickly determine whether or not electricity is being supplied to the radiator fan in this situation.
Reason #6: Coolant Issues
The possibility of air entering the system increases if the coolant level is low, and the coolant temperature sensor may fail to measure the coolant temperature accurately. It is necessary to replace the coolant to its optimal level if it has become low in the system.
Your engine may overheat and seize if you do not follow these instructions. Incorporating a routine flush of the radiator with vinegar or baking soda can prevent such issues by removing corrosive deposits. A seized engine often entails expensive repairs, a cost that may be prohibitive for the average person.
Reason #7: Radiator Fan Motor Not Working Correctly
It is possible to test the radiator fan by connecting it to an alternative power source, such as direct battery power, to see whether the problem with the fan remains.
Start by removing the wire connector from the wall outlet or power supply. Inspect the wires to ensure they’re all power lines, and none are ground wires.
Next, connect the negative battery terminal to something like the fan connection to the ground side. Then, connect the positive battery terminal to the other wire of the fan connector. Look in your car’s repair manual to determine whether your vehicle has a 4-wire termination or 3 terminals, with two for power wires and one for ground wires, as described above.
Your radiator fan should begin to operate as soon as the battery is connected. If your radiator fan does not begin to operate with direct power or only operates at a very low speed, you should check the terminal for damage and incoming voltage.
Reason #8: Clutch for The Fans
The fan clutch, which keeps the fan attached to the engine and assists in its rotation, should not be overlooked. After some time, the springs in the fan clutch may corrode or get worn. A clutch failure is the most common reason for the fan failure if all other components appear to be functioning correctly. If it is the source of the problem, it really should be replaced as soon as possible. Otherwise you will have to install new radiator and fan into your car.
FAQs
Should The Fan Be on If the Air Conditioner Is Running?
It is most energy-efficient to leave your fan set to AUTO mode. Whenever the system is turned on, does the fan turn on? If your fan is running continuously, moisture has no opportunity to seep outdoors. This recirculates back into your home, where your air conditioner must work overtime to remove any more moisture.
In What Circumstances Does My Fan Turn on Along with The Air Conditioning?
In this case, the thermostat is not working properly. If the fan and cooling system are operating when they shouldn’t be, there’s a good probability the thermostat needs to be changed. A short circuit or malfunctioning relay switch might have occurred.
Conclusion
No matter what the issue is, a faulty thermostatic switch, fan resistor or temperature sensor: the good news is that these are all inexpensive parts that you can find and replace on your own, without having to undergo the ordeal of taking your car to a local repair shop and spending big bucks.
In no time, you should see your Radiator Fan switching on as the car heats up, regardless of whether the AC is switched on or off!
