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 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 do you test a blower fan 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.
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 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 if your blower motor relay is 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.
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 many volts should a blower motor receive?
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.
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.
Does a blower motor have a relay?
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.
What controls the blower motor on the furnace?
A fan limit switch is a component of a furnace system that determines when the furnace blower assembly for hot air turns on and off. Essentially, this means that it determines when the hot air should be blown through your ventilation system. The fan limit switch also has two other functions.
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.
Does a blower motor resistor have a fuse?
A fuse is often located on the resistor board. The fuse only protects the low and medium blower speeds. High speed will still work if the resistor fuse is blown.
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 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).
Does a blower motor have a relay?
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.
Where is the best place to find the location of a blower relay?
The blower motor relay is generally located in the under-hood fuse box or in the under-dash fuse box. A blown fuse can mimic relay failure.
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.
What should the amps be on a blower motor?
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.
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).
What would cause a furnace blower not to kick on?
Make sure that the power cord hasn't melted or a fuse hasn't been blown. If your cables are looking fine, try unplugging the fan for a few minutes and then plugging it back in again. Sometimes, this process can reset the motor and solve your furnace problems.
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 do I know if my blower motor resistor is bad or blower motor?
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.
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.
What is a blower motor relay?
Blower motors are a common component in a home, commercial, and automotive HVAC systems. The blower motor relay is an essential component in a functioning HVAC system. Replacing a malfunctioning relay restores your system’s ability to keep your home, building, or vehicle comfortable.
How do you test a blower motor resistor?
Here are some tips on how to test your blower motor resistor: Start by looking for the blower fan resistor. A repair manual can tell you where its location is in your vehicle’s make and model. Inspect the resistor visually. Look for obvious signs of corrosion and burns from overheating.
How do you check if a fan motor is working?
A voltmeter connected to both ends of a resistor while current is passing through it to a load will measure the amount of voltage being “dropped” by the resistor. Finally, with the fan switch on the highest speed, the fan motor is receiving system voltage (14.5 with the engine running).
Why does my blower motor keep blowing fuses?
Thus, blown fuses could be a sign of relay issues. Blower motor relays handle a large amount of current. Malfunctioning relays aren’t able to distribute their load properly.
Below you will find two interesting articles on a similar topic 👇
Why has my blower stopped working?What causes a blower motor fuse to blow?
