In a blower motor, the relay supplies the power that allows the fans to circulate warmed air. Essentially an on/off switch, the blower motor relay's reactions start and end the heating process in HVAC systems by controlling the flow of current between the power source and the motor.
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 does blower motor relay do in car?
The blower motor relay is the electrical switch that is used to supply the power for the vehicle's blower motor. The blower motor is the component responsible for pushing air through the vents of your vehicle's heating and air conditioning systems.
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.
What causes blower motor relay failure?
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.
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 does blower motor relay do in car?
The blower motor relay is the electrical switch that is used to supply the power for the vehicle's blower motor. The blower motor is the component responsible for pushing air through the vents of your vehicle's heating and air conditioning systems.
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 know if my blower motor relay is bad?
If you have a faulty blower motor, you may experience low airflow from the vents, even when the fan is on high. There will be no air coming from the vents if your fan isn't working due to a bad blower motor resistor. Blown relay circuit fuses or melted relays are more serious signs of a bad blower motor relay.
How do you tell if a blower motor 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 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.
Is there a fuse that controls the blower motor?
Many vehicles have two fuses for the blower motor, one in the interior fuse block and the other under the hood. The blower motor is usually under the dashboard on the passenger side.
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.
Is there a relay for the blower motor?
In a blower motor, the relay supplies the power that allows the fans to circulate warmed air. Essentially an on/off switch, the blower motor relay's reactions start and end the heating process in HVAC systems by controlling the flow of current between the power source and the motor.
How do you check a relay?
The only tool required to check a relay is a multimeter. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located).
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.
Is there a fuse that controls the blower motor?
Many vehicles have two fuses for the blower motor, one in the interior fuse block and the other under the hood. The blower motor is usually under the dashboard on the passenger side.
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 does blower motor relay do in car?
The blower motor relay is the electrical switch that is used to supply the power for the vehicle's blower motor. The blower motor is the component responsible for pushing air through the vents of your vehicle's heating and air conditioning systems.
What causes blower motor relay failure?
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 if a relay fails?
If the relay fails it will cut off power to fuel pump and ignition system, which will result in a no power, and therefore no start condition.
Will a bad relay still click?
If your starter relay has gone bad, the electrical signal will never make it from the battery to the starter motor. As a result, your engine won't turn over - no matter how many times you turn the key. A faulty relay often produces an audible clicking sound when you turn your car.
How much does it cost to replace a blower motor relay?
The blower motor is operated by an electrically operated switch, called a relay. If the relay fails, the motor's fans will not blow conditioned air into your car. Fixing the relay usually costs around $50 to $80. So, if the blower motor relay fails, you could be left sweating or shivering.
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.
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.
Where is the resistor located in blower motor?
The blower motor resistor is usually extremely easy to access, but the hard part can be positioning your body inside the car to remove the part. The resistor is at the bottom of the HVAC housing or just behind the glove compartment.
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