Question: What can cause a blower motor relay to go bad?

Blower motor relays tend to wear out over time from the stress of constantly flicking back-and-forth. These signs indicate a possible issue with the blower motor relay. When the blower motor does not respond at all, it may not be due to mechanical failure within the motor itself.

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 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.

What relay controls the blower motor?

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.

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Why does my blower motor only work on high?

Most car manufacturers use a series of resistors to make the heater blower motor run at different speeds. And when one or more of these resistors burn out, you’re usually left with only one heater blower motor speed—high. The resistor module is easy and inexpensive to replace.

What happens when blower motor resistor goes bad?

A bad or failing blower motor resistor hampers the efficiency of the heating and air conditioning system. A working resistor can shift between speed settings according to the user’s preference. If one of the resistors is burned out, the only speeds that will work are the speeds above the burned out resistor.

Why will a blower run on the on position and not on auto?

Other Blower Fan Won’t Run Problems

The fan will run and blow warm air but only in FAN or FAN ON mode – delivering heat – but NOT in AUTO mode. This is a bad temperature sensor in the unit; replace the fan limit controller.

Why does my blower motor kick on and off?

…you most likely have a bad fan limit switch. Your furnace fan limit switch is basically a control system that determines when the furnace blower assembly should turn on and off. … So if your furnace blower is turning on and off when the furnace isn’t in a heat cycle, it usually means the fan limit switch is defective.

Why is my blower not working in my car?

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.

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Where is the blower motor fuse and relay?

The blower relay is located near the front of the fuse block and is labeled “Blower.” Inspect the center of the relay. If the metal rod inside is broken, the relay will need to be replaced.

Is there a fuse for 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.