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.Testing the blower motor of your vehicle using a multimeter Use the ignition key to turn on your engine the run set to read the purple wire for current. Next, having set your multimeter to DC power, turn either your heater or cooling energy to full strength. When your multimeter reads no current, then your blower motor is defective. More items...

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 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.

What is the 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 happens when 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.

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.

Is there a fuse for blower motor?

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.

Is there a fuse for the blower motor?

Where is the blower motor fuse and relay?

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 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.

Should I replace the blower motor and resistor at 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.

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.

What relay controls the blower motor?

The blower motor relay controls the current used to power the blower motor, and is subject to the constant on and off switching.

What happens when a blower motor goes bad?

The blades of the fan are made of plastic and they can get damaged easily. If it happens, you will hear unusual noises like slapping or sudden pop coming from behind the vent. Problems with the airflow have signs such as ongoing whirring, getting louder when you increase the fan speed.

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.

Why do I have to hit my blower motor to work?

Blower motor only start working after i hit a bump. In most cases that is a sign of worn down blower motor brushes not making a good contact. In some cases the blower motor/resistor pigtail could cause erratic operation of the blower motor too.

What relay controls the blower motor?

The blower motor relay controls the current used to power the blower motor, and is subject to the constant on and off switching.

How can I tell if a relay is bad?

You want to feel and listen for any clicks. If you feel and hear clicks, the relay works on one side – the side with the energizing circuit and coil. However, if there was no sound from the horn, the relay has a problem along the contact circuit.

How do you test a blower relay?

Connect a test light or multimeter to the ground (black lead). Turn the ignition key to the on position (engine off), and remove the relay. Using the probe, test all terminal sockets in the relay connector. Two of the four should have power.

What is the difference between a fan motor and a blower motor?

What Is a Blower Motor? Unlike the condenser fan motor, the blower motor is located indoors. It's the component that blows cool air through the ducts and into different parts of your home. So it's essentially your air mover.

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.

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.

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.

Why is my blower fan not working?

If you see or hear the fan turn on, your blower motor is not the culprit. If the fan does not start, you have a wiring issue (circuit breaker trips) or motor problem (circuit breaker does not trip). While your thermostat may be at fault, only an HVAC technician can diagnose and remedy the issue correctly.

How can I tell if a relay is bad?

You want to feel and listen for any clicks. If you feel and hear clicks, the relay works on one side – the side with the energizing circuit and coil. However, if there was no sound from the horn, the relay has a problem along the contact circuit.

How do I test the blower motor on my car?

The blower motor in your car is usually located behind your vehicle’s glove compartment. Disconnecting the positive and negative power supply is the first thing to do. The black wire is normally negative. With your multimeter (Ohm scale), you need to take the positive lead of the multimeter to test the negative black cable.

How to test a blower resistor with a multimeter?

If you want to do a quick test of the blower resistor, you can check the resistance of each of the resistors with a multimeter as follows: set the tool to read ohms (a measurement of resistance) and connect one of its probes to the common output terminal of the resistor.

How do you test a motor with a multimeter?

Set a Digital Volt Ohm Meter (DVOM) to the ohm setting and test the motor while the power is shut off. On average, most motors will have little resistance. Thanks! How do I check and find out with a multi-meter whether a motor is faulty or not?

What to do if your blower motor does not work?

When your multimeter reads no current, then your blower motor is defective. If the multimeter identifies a current, then further testing of the blower motor is needed. The next thing is to remove the cover of the fuse panel access, located next to the shifter of the passenger’s side in the footwell.