what is the cooling fan resistor for

by Francis Batz I Published 3 years ago Updated 3 years ago

The purpose of the cooling fan resistor is to remove heat from the engine's coolant and from the A/C refrigerant. The resistor does this by drawing air through the radiator and air conditioning condenser. The second fan is powered by the cooling fan resistor as well, and always runs at a high speed.

The resistor is powered by the ignition and enables the cooling fan to run at slow speed. Once the engine reaches a manufacturer-predetermined temperature, a temperature switch indicates to the cooling fan resistor that the fan should run at high speed to draw more air through the radiator and provide extra cooling.

Full Answer

Do cooling fans really work?

They are remarkably effective at cooling any room. With fans that work like ac, you’ll get a quick lift when it’s time to combat the cold winters or hot summers. The problem is, running these units throughout the year isn’t economical. Sooner or later, you’ll realize how much they burn through your power bills.

What is the best cooling fan?

How to choose the best ceiling fan for your home

Find the right design. “One of the first things you want to look at is where the ceiling fan is going to go. ...
Measure up. “Ceiling fans are a great addition for airflow. ...
Complement your cooling. “Ceiling fans are powerful and can also be used in conjunction with an air conditioner to increase their efficiency on those scorching hot days and nights.

What is the function of cooling fan?

Engine overheating. Engines generate an enormous amount of heat and as a result are subjected to very large temperature swings if this switch does not operate effectively.
Check Engine Light comes on.
Broken or shorter signal wire.

How to replace the cooling fan?

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Can I bypass my cooling fan resistor?

The high speed circuit has no series resistor, the Fan Resistor, and needs a 50A fuse. If you short out/bypass the Fan Resistor you may exceed the 30A fuse value. If you replace the 30A fuse with a 50A fuse you may exceed the wires current rating associated with it if it is not the correct gauge wire.

How do you test a radiator fan resistor?

3:023:34WHAT RADIATOR FAN RESISTOR IS. WHAT IT DOES AND ... - YouTubeYouTubeStart of suggested clipEnd of suggested clipOkay it is goes all the way like that and we just slide it up. So that's where it stays.MoreOkay it is goes all the way like that and we just slide it up. So that's where it stays.

What is a car fan resistor?

The blower motor resistor is responsible for controlling the blower motor speed. In the past, this was done by varying the voltage supplied to the blower motor. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.

What controls the radiator fan speed?

In addition to the power, ground, and tach signal, 4-wire fans have a PWM input, which is used to control the speed of the fan.

How do I know if my cooling fan resistor is bad?

Symptoms of a Bad or Failing Cooling Fan ResistorEngine overheats.Cooling fan speed issues.Cooling fans never turn off.

What are the symptoms of a faulty cooling fan switch?

Common signs include engine overheating, the Check Engine Light coming on, and a broken or shorter signal wire.

Will a blower motor work without the resistor?

No air comes out of the vents There are instances where a bad resistor will prevent the current from reaching the blower motor altogether. Without any power, the motor won't run. As a result, the blower fan stays still and silent, and no air blows out of the vents.

What happens when a blower motor resistor fails?

If the resistor shorts or fails, it may cause the blower motor to remain stuck on one fan speed. The heating and air conditioning systems may still function at one speed, however the resistor will have to be replaced in order for full functionality to be restored.

What causes blower motor resistor failure?

Causes of the Final Stage of Blower Fan Failure In most cases, the blower fan resistor is failing either due to overheating or corrosion. If the blower fan fails, your car will not blow any forced air. However, sometimes the problem can be with the blower motor itself.

What happens if a cooling fan resistor fails?

If the cooling fan resistor fails or has any issues, it can cause power to be cut off from the cooling fans, which can lead to overheating. Any sort of overheating issue should be tended to as soon as possible to avoid the possible engine damage. 2. Cooling fan speed issues.

How to tell if a cooling fan resistor is bad?

Usually a bad cooling fan resistor will produce a few symptoms that can alert the driver of a potential problem that should be serviced. 1. Engine overheats. One of the first symptoms of a potential problem with the cooling fan resistor is engine overheating. If the cooling fan resistor fails or has any issues, ...

How does a cooling fan work?

Virtually all modern vehicles built today use electric cooling fans to help pull air through the radiator to keep the engine cool. Once the coolant temperature sensor detects that the engine temperature has exceeded acceptable levels, the cooling fans will be activated to keep the engine cool. Many vehicles come equipped with cooling fans that operate on more than one speed setting. This is made possible by routing their power through the cooling fan resistor. The cooling fan resistor is an electrical resistor that limits power to the fan in steps, so that the fan can operate at different speeds according to the cooling system’s demands. Since power to the cooling fan is sometimes routed through the cooling fan resistor, when it fails or has any problems, it can cause issues with the regular operation of the fans, which can lead to overheating. Usually a bad cooling fan resistor will produce a few symptoms that can alert the driver of a potential problem that should be serviced.

Why does my cooling fan overheat?

Since power to the cooling fan is sometimes routed through the cooling fan resistor, when it fails or has any problems, it can cause issues with the regular operation of the fans, which can lead to overheating. Usually a bad cooling fan resistor will produce a few symptoms that can alert the driver of a potential problem that should be serviced.

Why does my car keep cooling fans on?

If the resistor shorts or fails, it can cause the cooling fans to stay on even when they are not supposed to. In certain cases, the cooling fans may even stay on when the vehicle is turned off, and will create a large parasitic drain that will eventually kill the battery.

Why do cooling fans stay on when the car is turned off?

In certain cases, the cooling fans may even stay on when the vehicle is turned off, and will create a large parasitic drain that will eventually kill the battery. The cooling fan resistor is an important component, as it is one of the components that routes power for the cooling fans.

Why does my fan only work on one speed?

Another symptom of a possible problem with the cooling fan resistor is issues with the cooling fan speed. If the resistor breaks or has any issues it may cause the fans to only function on certain settings. The cooling fan resistor is meant to send power to the fans in steps, so that the fans may operate at different speeds. If any of the individual steps or switches fail, it will disable the cooling fans from operating on that speed setting. You may notice that the cooling fans only operate at one speed, when they used to operate on two or more.

Why do we need a cooling fan resistor?

A lot of manufacturers use cooling fan resistors in order to offer multiple fan speeds on a single fan assembly or to control dual fans. By employing the resistor, different amounts of voltage can be supplied to a motor, thus changing the speed of the fan.

How to hold a fan resistor in place?

The resistor for the cooling fan motor can be held in place by any combination of clips, screws, or bolts. Remove the hardware that is holding the resistor into place and unplug the electrical connector. Note: Some manufacturers will use a crimp style electrical connector to attach the wiring to the cooling fan resistor.

Why does my cooling fan stop working?

If the engine is overheating or the cooling fan does not operated at all possible speeds , there may be an issue with the resistor. If the resistor is broken, the cooling fan may never turn off.

Can a cooling fan be connected to the ignition?

Warning: The cooling fan is capable of operating with the ignition key in the off/park position. Also, the cooling fan relay typically has battery voltage supplied to it. For both of these reasons, it is highly recommended that the vehicle battery be disconnected for your safety.