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How do you tell if it's the blower motor or resistor is bad?

Author of the blog (work in a car repair shop)
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How do you tell if it's the blower motor or resistor is bad?

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.The most common symptom of a bad blower motor resistor is that you will only notice that your blower is working on the highest speed setting or that it won’t work at all. The main symptoms of a bad blower motor resistor include: Only One Speed From Blower Motor

How do I 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.

What happens when a blower motor resistor goes out?

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. When the blower motor doesn't get power, air pressure can't be produced. You are left with a heater or air conditioner with nothing coming out of the vents.

Is there a fuse for blower motor?

Will a blower motor work without the resistor?

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.

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.

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.

How many ohms should a blower motor have?

According to the service manual, it must be around 4-5 ohms. In our case the ohmmeter shows open circuit, which means the resistor has failed. Sometimes, a blower motor resistor might fail due to problems with the blower motor itself.

How do you test a resistor?

To test individual resistor values (outside a circuit), connect the multimeter probe wires to the resistor's two terminals—it doesn't matter which way round, as resistors are not directional components. Make sure the multimeter dial is in resistance measuring mode. Then check the value on the multimeter.

What happens when a 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.

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.

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.

How do you test a resistor?

To test individual resistor values (outside a circuit), connect the multimeter probe wires to the resistor's two terminals—it doesn't matter which way round, as resistors are not directional components. Make sure the multimeter dial is in resistance measuring mode. Then check the value on the multimeter.

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.

How long does it take to change a blower motor resistor?

The average cost to replace the blower motor resistor at a repair shop is between $44 and $55 in parts and $70 in labor costs, for a total cost of around $114 to $125. On the other hand, you can easily fix the blower motor resistor at home in about an hour (even if you're a beginner) and for around $70.

How long does it take to replace a blower motor in a car?

How Long Does It Take To Replace A Blower Motor In A Car? It generally takes about 4 hours for an experienced technician to do a blower motor replacement. If you are doing it on your own in your garage with common tools, you can expect the job to take 6 hours or more.

Can a bad blower motor resistor cause no heat?

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 failure?

Blower motor breakdown can be the result of anything from old age to failed bearings, high amp draw, electrical failure in the windings, dirt accumulation, and more. “The most common cause is dirt accumulation due to lack of maintenance,” said Tom Beaulieu, president of Bay Area Services Inc.

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 motor is bad on a multimeter?

What happens when a resistor fails?

When a resistor breaks down, current typically flows through the burnt resistor without any resistance and thereby passes unchecked. Other components in the circuit may become damaged from the excess current flowing through.

How does a resistor fail?

Resistor failures are considered to be electrical opens, shorts or a radical variation from the resistor specifications. The failure modes experienced vary with the type of construction. A fixed composition resistor normally fails in an open configuration when overheated or overly stressed due to shock or vibration.

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.

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.

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.

What causes heater blower not working?

If little air is coming through the vents (hot or cold), then it could be because the blower motor for the fan or a switch or resistor that controls fan speed isn't working. Another cause might be that the electronically controlled “blend doors” that direct air flow are stuck or broken.

What are the symptoms of a bad blower motor resistor?

1. Blower motor stuck on one speed A common symptom of a faulty blower motor resistor is a blower motor that is stuck on one setting. The blower motor resistor is the component directly responsible for controlling the blower motor fan speed. If the resistor shorts or fails, it may cause the blower motor to remain stuck on one fan speed.

What causes a blower motor to stop working?

If your blower motor cannot change to certain speeds, check both the resistor and the switch on your dashboard. The most common failure points are the resistor and the motor itself. There are instances where a bad resistor will prevent the current from reaching the blower motor altogether.

Do I need a new blower resistor?

Some of my friends say I need a new blower resistor because that controls the air flow or something and others say blower motor. I believe if I am moving on "no circulation" and the air is coming through the vents, then the blower motor is fine. Or that its just my vents are open and the air is coming from somewhere else.

How do you test a blower motor resistor?

How do I test a blower motor resistor? To test a blower motor resistor, you need to use a multimeter. Either you can measure the resistance of the input and output pins of the resistor, or you can measure the voltage coming out of the resistor.

Below you will find two interesting articles on a similar topic 👇

How do I know if my heater fuse is blown?

What does a blower do on an engine?

Tired of looking for a video for your question?

Video Answer below 👇

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