Almost every road-going vehicle has a car radiator. Car radiator fans are an important piece of equipment in the cooling system; the fan blows off heat from the radiator fins to assist the operation of the engine at average operating temperature.
A bad radiator fan can be very destructive to your car engine. Trouble from overheating could lead to the impairment of several components, causing the need for a costly engine repair.
When you start the engine, the fan will not blow until the engine gets to an average operating temperature. This could take between 5 to 15 minutes depending on your vehicle model. You can cut this time if you place a load on the engine.
A common example is to turn on the air conditioning system. But then, what happens if the radiator fan doesn’t work after you reach the engines normal operating temperature and after turning on the AC? Of course, that can happen, but it is not normal.
You may ask, what happens when your radiator fan stops working? We’ll find out as we progress along the subject. But first, let’s take a look at what could cause the radiator fan not to work when the AC is on.
What Causes the radiator fan not to work when ac is on?
There are a few issues that can cause a radiator fan not to come on even when the AC is on. Either way, if the fan doesn’t blow at all when the AC is off or on (which is likely), the fan is completely bad.
You might be asking, does the radiator fan come on when the AC is on? Yes, the radiator fan should come on when the air conditioning is engaged.
The following causes: a blown relay, bad temperature switch, blown fuse, damaged wiring harness, and low coolant temperature can cause the car radiator fan not to come on when the AC is on or off.
The last possible thing on the list may surprise you. It may be an issue if the fan blows every other time but does not engage when the AC is on.
#1. Blown fuse.
Fuses protect electrical and electronic components from electric bridges and surges. A blown fuse occurs when there is a surge in current that can damage an essential electrical component.
If excess current comes through, the corresponding fuse has a metal strip that will cut, preventing the power from getting to that key component. A blown fuse is when the strip is cut.
#2. Bad temperature coolant sensor.
Many automobile manufacturers have the powertrain control module that is capable of overseeing the complete radiator fan operation; on the other hand, some have used other separate modules to activate and deactivate the radiator fan.
Both manufacturers have temperature sensors that measure coolant temperature, and then act upon that information from the PCM or in the case of the other manufacturers, their separate module.
If this sensor is not working properly or has completely failed the engine control unit (ECU) does not know when the coolant gets too hot, and does not know when to start the radiator fan.
#3. No coolant or low coolant.
If your radiator fan is not functioning, but you are not overheating, there may be no coolant in your reservoir.
The reason is that temperature sensors in vehicles do not directly read how hot the engine temperature is; sensors read the temperature of the engine coolant to determine engine temperature.
On the other hand, when the coolant level gets low, if the reservoir is full of air, the temperature sensor will send incorrect readings. This is the first or second thing you should check when the radiator fan will not turn on even with the Ac running.
#4. Blown relay.
As the radiator fan draws a lot of electrical current out of the electrical flow running throughout the vehicle, most auto manufacturer use a relay that maintains that electrical current.
However, the relays can fail or become damaged and not allow current to pass to the proper components.
A fuse box or a separate box near the fuse box in the engine bay usually has the cooling fan relay fuse. However, you get find where the relay is located on your owner’s booklet, and examine it.
#5. The bad fan controller module.
Some manufacturers, as previously stated, use a car fan control module to control the cooling fan. The car fan control module is in the engine bay. It fails from either heat from the engine compartment or corrosion/dust depending on where its in your car.
#6. Broken radiator fan.
If the cooling fan does not work when the AC on or off, the fan itself is the problem. The radiator fans have an electric motor Use to spin them.
If the motor fails, there’s no motor power to the fan blades to spin. If one radiator fan is working, you should checking the other radiator fan. The motor could be pretty bad, or it could be a wiring issue in the wiring harness.
#7. Bad wiring connections.
If the cooling fan is not turning on, and the engine is really hot; it could be bad broken wiring or bad wiring connections.
#8. Bad AC high-pressure sensor.
There are many vehicle manufacturers, which indicate many different underhold working principles.
For instance, your cooling fan may not work, especially if the air conditioning is running, could probably indicates you have a bad expansion valve on the AC high-pressure line.
Some cars may not run like this. But I once experienced this with a customer driving into my garage to fix the air conditioning system of a 2003 dodge caravan SE.
After my repair job the AC was working perfectly. However, the electric fan never came on. So I tested the voltage and relay, and examined and inspected the fan. The fan looked ok, but no voltage and no relay.
After running back and forth for some minutes. I finally pulled the high-pressure sensor out of the vehicle and thoroughly cleaned it.
This action solved the problem. So if you have been wrestling with this problem. Check the AC high-pressure sensor, that may be the problem with your cooling fan not working, when your AC was turned on.
How To Fix Radiator Fan Not Working When Ac Is On
There are numerous reasons why your radiator fans are not blowing air when your ac is on, so you have numerous ways to fix the problems. Let’s look at how to get the radiator fan to turn on in these situations.
#1. Replace damaged cooling fan.
When you have a damaged cooling fan, the reasonable thing to do is replace it. Although, if the blade is damaged, you may just want to replace the blade. However, it is usually the electric motor that is damaged. If it is the motor, then you have to replace the entire fan.
First, test the fan by rattling the electric fan motor and see if the motor shakes. The fan motor should be solid and intact.
#2. Inspect the relay and fuse.
Find the fuse that protects your cooling fan. You have a fifty amp fuse that is going to protect the cooling fan.
First, review the article that shows what a blown fifty amp fuse looks like. Find the cooling fan relay and inspect it. If you do not understand how to determine if a relay is dead, check out this article on “how to tell if a relay fuse is blown”.
Once you identify a blown fuse or relay, replace it with a good fuse of the same amperage. Replacement relays and fuses are some of the cheapest components on an automobile. Relays and fuses present one of the simplest solutions to fixing the fan claim.
#3. Check coolant level and the temp sensor.
Check to make sure the reservoir has adequate coolant. The coolant and the temperature sensor work in unison for accurate temperature reading.
The temp sensor is faulty if the coolant is at the right level. However, do not pass judgment on the temp sensor is broken without seeing other signs that indicate a broken temp sensor.
Knowing what the temperature gauge is reading is important to understand what is and is not normal. If you decipher the temp sensor is bad, but simply replace it.
#4. Examine the wiring and the fan controller module.
Examine the wiring harness that connects the fan controller module and the fan itself. If you see a burnt, frayed or disconnected wiring, fix any damaged wiring and see if your problems are resolved.
Lastly, a dead fan controller module will not allow the fan to blow air regardless of whether the fan is OFF or ON. Therefore, inspect the module and replaced it if you need to.
As reiterated above as well, if your radiator fan is not blowing air when the air conditioning is turned ON in a 2003 dodge caravan, inspect and clean or replaced the high pressure line sensor on the ac lines.
FAQs.
Q: Does the radiator fan operate when AC is on?
Yes. Both the radiator and condenser cooling fan should start as soon as the air conditioning system is turned on. For example, it is normal for the cooling fan to turn on when the engine is under load or after it reaches operating temperature.
Q: Does the condenser fan operate when AC is on?
If you’re like me, there’s no way you are going to enjoy your summer rides while the air conditioning system is not working properly.
It becomes depressing driving around with no cooling inside the cabin. The AC unit has several components of the system that together allows it to work properly.
Anytime the AC is turned on, the fan should be running because it works in conjunction with other AC system components. Therefore, if you start the vehicle and turn on the air conditioning system, but the fan isn’t running, find out why, and fix it.
Q: Does the thermostat control the radiator fan?
The thermostat in a car is an important part in keeping the car at proper temperature. The thermostat opens and closes when it is needed.
When the coolant temperature inside the engine is lower than average operating temperature, the thermostat closes, and prevents the coolant in the radiator from going into the engine.
When the coolant inside the engine reaches normal operating temperature, the thermostat will open, and cold coolant can then travel toward the engine and hot coolant back to the radiator. At this point, regardless of the status of A/C, the radiator fan will start blowing.
However, if the thermostat is stuck in a closed position, it will not allow coolant to flow, which may send false feedback to the powertrain control module that the engine has not reached normal operating temperature, thus preventing operation of the fan.
Q: What is the difference between a condenser fan and a radiator fan?
The condenser fan and radiator fan disperse heat from the condenser and the radiator. Both fans will turn on simultaneously when you operate the air conditioning systems, and operate depending on engine temperature, so they are essentially the same thing.
However, in some vehicles, the condenser fan only operates with the A/C on, and the radiator fan operates depending on engine temperature.
Q: What happens if the condenser fan does not operate?
If the condenser fan does not operate, it may be due to a bad capacitor, defective contactor, burnt motor, or damaged fan.
If the condenser fan does not start for any of these reasons, especially during the summer, a few components of the air conditioning system may overheat and trip the circuit breaker. If the circuit breaker trips, the whole unit will shut off.
Q: What sensor controls the radiator fan?
In most automobiles, the radiator fan is controlled by the powertrain control module, which inputs readings from the engine temperature sensor.
In other models, through which the radiator fan is controlled by a cooling fan control module.
Furthermore, the powertrain and cooling fan control modules are able to make proper inputs and decisions by collecting readings and input from each of the element within that specific system and any other related systems and sensors.
Final Words
The radiator or cooling fan is essential for preventing overheating of the engine and air conditioning systems. Radiator cooling fans maintain the engine at a proper temperature, but they can fail and lead to engine overheating.
Naturally you do not want this to happen. We have given you the causes of a radiator cooling fan not working when AC is on, as well as the solutions to the problem.
Now follow the above steps to identify and fix the bad part or item. Finally, if you do not have the confidence in yourself, take your vehicle to a mechanic who can be anther and solve the issues with the cooling fan.