What Causes Blower Motor Resistor To Fail

Over time that heat can cause the resistor to fail naturally. A usual place for water to enter into this area is a loose or missing weatherstrip under the upper cowl panel.

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A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system.

What causes blower motor resistor to fail. Trent one of the biggest reasons for blower motor resistors to have shorten life is actually because of faulty blower motor drawing too many amps some times melting wiresplugs heating up resistors shortening their life. From the op does anyone have insight into what is the root cause and repair of. If the blower motor resistors internal components fail it may cause the blower motor to malfunction or not function at all on one or more of the settings.

The higher current can make the jump across the resistor contacts that are going bad and get the blower motor to engage. If the blower motor looks like it is rusty or the resistor keeps burning up then it is most likely water intrusion. The most common symptom of a failed blower motor resistor is when the heater fan only runs at the highest speed setting 4 or 5 and doesnt work at low speeds.

Apparently they got in through the air intake. By its very nature resistors resist the flow of electricity much like a flow restrictor in a pipe. A common cause for these failures is that water is getting into those components.

I hope this helped you out if so let me know by pressing the helpful button. When the resister of the blower motor starts to fail the motor operates only intermittently. In some cars a failed blower motor resistor can cause a heater fan to stop working completely.

Just pulled my blower motor resistor due to only high speed operation. Failure was caused by dead leaves packed around the resistor blocking cooling airflow. What causes a blower motor resistor to fail.

However as a side effect of reducing current flow resistors generate heat. This can also be caused by a blower motor switch so a proper diagnosis is highly recommended if you are uncertain of what the issue may be. As the fan speed is one of the most frequently adjusted settings of the air conditioning system the blower motor resistor is put under constant stress which can cause it to eventually fail.

This often presents itself as the blower fan not kicking on until the engine is producing a certain level of electric current. Many dodge forums tell of this problem. The blower motor resistor which also goes by fsr final stage resistor or by fsu final stage unit is known to fry itself in almost every single e46 3 series e39 5 series and e38 7 series bmw.

The root cause of this common part failure. In most cases a blower motor resistor fails due to corrosion or overheating.