Why Car Blower Motor Works Intermittently? (Causes & Fix)

The blower motor is one of the HVAC system’s main components that push hot air throughout your car when running the heating system.

The AC evaporator allows providing cool air when you start the air conditioning system. 

But, sometimes you’ll face that your car blower motor won’t work properly that means car blower motor works intermittently. For this, It’ll hamper your driving experience, and you won’t get proper airflow through the car vents.

So, Here in this article, I’ll explain to you some possible causes of this problem and how you can fix those issues.

What is the purpose of a Car Blower Motor?

The blower motor is the main electric motor in the car HVAC system. The purpose of this blower motor is to allowing blowing air to come through the vents by transferring the electrical current.

It uses a motor resistor and switch to control the speeds of airflow. For this, You can operate and regulate cabin temperature according to your preference.

In addition, It’s not only important for operating an air conditioner system on your car. Without proper functioning of the blower motor, your car might face an overheating problem that affects your car engine.

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How will I know Car Blower Motor is working Intermittently?

You can easily identify the symptoms by observing a few things. Here are few signs that indicate your car blower motor Works Intermittently.

Blower Stops Working or Takes Time To Start:

Whenever you click the switch, you’ll witness that it suddenly stops working or takes time to start the motor.

In addition, The blower motor might turn on and off randomly while you’re driving the car.

Noise Comes Behind The Vent:

Noise Comes Behind The Vent

Another thing you’ll notice is that it makes a sound as it operates on a low voltage, and you’ll get noise from behind the vent, such as a sudden pop.

Also, The noises sometimes change according to the fan speed. If you turn on the fan at full speed, you’ll hear louder sounds and whirring noises that indicate the problem with the blower motor.

Often Start Working:

Another intermittent operation clue is that the motor will often start working after a bang on the heater box.

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Why Car Blower Motor Works Intermittently?

Several reasons can lead to car blower motor works intermittently. Here are few causes of this problem:

Ignition Switch Issue:

The problem might be with the ignition switch. To find out whether the problem is on the ignition switch or not, try wiggling or moving the key around the ignition; if you find a sign that it affects the blower motor, then it’s okay.

Otherwise, The ignition wire or contacts could be wrong, which leads to the problem.

Blower Motor Fan Issue:

The fan motor itself can cause this problem. After starting the engine, if it never quits after running a while, then the problem is on the fan motor.

The intermittent operation is happened due to worn brushes inside the motor.

Also, If you need to bang on the heater box to start it, then it’s a potential clue of a bad motor. It happens because of burned connector terminals and overheating.

Bad Relay:

The faulty fan motor relay can be the cause of intermittent operation. 

Wire Issue:

The melted or faulty connector wire might create the issue.

Bad Motor and Resistor:

Sometimes the bad blower motor and the resistor are the cause of this problem.

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How To Know whether a blower motor resistor is bad or blower motor?

To ascertain whether a blower motor resistor is malfunctioning or if the blower motor itself is the issue, conduct the following diagnostic steps.

Blower Motor Resistor Issue:

This is a common problem in many cars. The most common symptom of a blower motor resistor is that when you start the heater fan, it only runs at the highest speed setting (4 or 5) and doesn’t work at lower speeds.

It indicates that your car blower motor resistor has an issue. Also, Sometimes the heater stops completely due to a bad blower motor resistor.

Blower Motor Issue:

Car Blower Motor
Source: EasyAutoFix

You’ll witness several symptoms which indicate that your car blower motor won’t work properly. Here are a few symptoms of the bad blower motor.

  • You’ll notice the weak airflow through the vents.
  • The blower makes a squealing or screeching sound when operating.
  • When using it, you’ll face the overheating issue, which means your Blower Motor in HVAC is facing trouble. 

Also, you can test the motor whether it works properly or not. For this, You need an multimeter.

If you get at least 4 to 6 volts at low speed and 12 volts at high speed, but the motor doesn’t turn on, that means your car blower motor has a problem or is jammed.

But, You need to test the whole motor circuit if it doesn’t show any voltage at all.

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How To Fix A Car Blower Motor That’s Working Intermittently? 

The solution to this intermittent problem depends on the causes. 

Easy Fix For Motor Problem:

If the problem is with your blower motor or it’s dying, you need to change it. Your local auto parts repair center can help you select the correct motor according to your car model. 

It’s a good idea to change the resistor and the dead motor even if it works perfectly because the connection wires might create an issue.

Car Blower Fan

Easy Fix For Fan Issue:

You need to change or replace the control panel for the fan problem. But, Only changing it won’t solve this problem completely.

Cut out all the mating connector terminals and replace those individually.

Otherwise, The resistance generates more heat, and it migrates into the controller and transfers the overheat into the new terminals. For this, you might face repeat failure.

Easy Fix For Wire Issue:

Also, Sometimes cleaning the whole wiring solves the issue, but if it doesn’t work, you need to change the resistor.

In addition, Change the burned or melted wires if you notice any and consider checking inline fuses.

Easy Fix For Relay:

If the intermittent operation occurs for the fan motor relay, the fastest thing you might do is find out similar one from an auto parts shop and replace it.


You’ll face several problems as a car owner. It’s very frustrating to having a problem with vehicle’s when you’re on the road. So, You need to prepare yourself for such a situation and educate yourself for such a condition.

For this, In this article, I talked about a common problem you might face: car blower motor works intermittently. In the above sections, I hope you learn a few common reasons why this problem arises and how you can solve those.

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