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. There are instances where a bad resistor will prevent the current from reaching the blower motor altogether.If the blower motor resistor fails, the blower motor will still work, but it will be stuck on one speed in most cases. If you remove the resistor completely, the blower motor fan will still work at one speed, in most car models. This is because usually the resistor is not used for the highest speed setting.
How do I know if I need a blower motor or a resistor?
Signs of a Bad Blower Motor Resistor Loss of HVAC fan control (total or certain speeds) The fan only works on its highest speed setting. No air coming from vents. Intermittent or inconsistent fan speed.
Why do you need a blower resistor?
Blower resistors are resistors which are used to control the fan speed of automotive blowers. The fan speed can be changed either by switching the blower resistor resistance mechanically using a rotating lever, or electronically by the air conditioning system.
What can cause a blower motor to stop working?
In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.
What is the difference between blower motor and blower motor 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 can cause a blower motor to stop working?
In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.
What happens when the blower motor resistor goes out?
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.
Should you replace blower motor and resistor at the same time?
We do suggest that you replace the resistor at the same time. It may not be critical, but this will keep the system more uniform. The issue may even be related to the resistor. If you know that it is not related to the issue, then you do not have to replace it.
Can a bad blower motor cause no heat?
Problems with Your Blower Motor or Blower Motor Resistor Without it, there's no circulation of air—hot, cold, or otherwise. The blower motor resistor is the part that controls the fan speed of the blower motor. Both of these components can fail, resulting in the heating system simply not working.
Is there a fuse for the blower motor?
How do you test a blower motor resistor?
Place one lead of the Ohmmeter on terminal 1 of the resistor. Place the other lead on terminal 2 and check against specifications. If this circuit is open, showing infinity on the Ohmmeter, the blower resistor must be replaced. Move the lead from terminal 2 to terminal 3 and check this reading against specifications.
Where is the blower motor reset button?
Locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. Be cautious as the housing may be hot. If the button is popped up, press it down.
How long should a blower motor resistor last?
The blower motor resistor is designed to last for the car's lifespan. In most cases, these resistors will wear out long before the car does. Usually, the wear that the blower motor resistor has is due to the constant use that it gets and the heat that it is exposed on a regular basis.
How do you know if a resistor is bad?
A good resistor should test within its rated range. A bad resistor will either show infinite resistance or a measurement far higher than its rated resistance. In either case the resistor is no longer functioning properly.
How much does it cost to replace blower motor resistor?
How much does a blower motor resistor cost? To replace the blower motor resistor, it would cost you anywhere between $50 to$150 – this includes the cost of equipment and labor. However, by doing it yourself at home, you can save up to $70.
What can cause a blower motor to stop working?
In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.
Can a bad blower motor resistor cause no AC?
No Air Coming From Vents The blower motor resistor controls the power to the system's blower motor. When it fails, it can cut off all power to the motor.
What happens if blower motor relay goes bad?
If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow. Any sort of electrical spikes or excessive current from a bad relay will blow the fuse and cut power in order to protect the system.
What does a heater blower resistor do?
The blower motor resistor in your car is the part that is responsible for pushing air through the vents when using the air conditioner or heater. The blower motor resistor is constantly put under stress which can cause it to eventually fail.
Why is my car blowing out cold air when the heat is on?
Low Coolant Level The coolant (usually a mixture of water and antifreeze) in your engine doesn't just work to keep the engine from overheating: It's also the source of heat supporting the heating system. If there isn't enough coolant in your system, the heater core will blow cold air into your car.
Does the blower motor control heat?
The blower motor is an important part of your vehicle's heat and air conditioning systems. Without it, you can't control the temperature of your cabin — not a dire consequence, but definitely a major annoyance in extreme heat or cold.
Where is the blower motor relay fuse located?
Under the instrument panel, look under the glove box. On the right side of the fender wall you will find another fuse box. The blower motor fuse is easy to replace.
How do I know if my heater fuse is blown?
You can quickly determine by checking resistance with a multimeter. A good fuse will have nearly zero ohms of resistance, if the fuse is blown there will be no reading.
How do you test a blower motor with a multimeter?
Turn off your vehicle, set your multimeter to Ohms, and check for resistance between the blower's positive and negative terminals. You may also turn the car key to run without starting the engine, put the cooling system at full blast, and check for DC voltage. If none of these produces a reading, the blower is bad.
Can I bypass 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 much does it cost to replace a blower motor resistor?
How much does a blower motor resistor cost? To replace the blower motor resistor, it would cost you anywhere between $50 to$150 – this includes the cost of equipment and labor. However, by doing it yourself at home, you can save up to $70.
What happens when a blower motor resistor goes bad?
Blower motor resistor problems. The most common symptom of a failed blower motor resistor is when the heater fan only runs at high speed and doesn't work at low speeds. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely. In most cases, a blower motor resistor fails due to corrosion or overheating.
Why is my blower motor not working in my car?
In this car, in the highest "4" fan speed setting, the resistor is bypassed and the blower motor is powered directly by the fan switch. That's why in some cars, the blower motor may still work in the "High" speed setting if the resistor is bad.
Is the heater blower motor resistor expensive to replace?
In the scheme of air conditioning and heater parts, this is one of the least expensive to replace. The heater blower motor resistor can often go bad because of a bad heater fan, and therefore you often have to replace both the heater blower resistor and the fan. It’s also not a difficult part to replace.
Where is the blower motor resistor on a car?
The heater blower motor resistor is often found beneath the dashboard. It is located in the heater and air conditioning compartment. It’s connected to the air conditioning system, where it can adjust the speed of the blower motor fan. It can also be found behind the glove box of some vehicles. Either way, you will find it close to the blower motor.
Below you will find two interesting articles on a similar topic 👇
How do I check an air conditioner for a blown fuse?How do you test a blower motor with a multimeter?
