Is a blower motor resistor supposed to get hot?

Asked By: Arne Grimmeissen | Last Updated: 19th April, 2020
Category: home and garden indoor environmental quality
4.1/5 (634 Views . 32 Votes)
Yes that resistor will get very hot. Most people don`t know this but it is faster to defrost the windshield on low or medium fan speed due to that resistor putting off heat. Also that resistor needs to be cooled off with the air flow or it will burn up .

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Similarly, you may ask, how do I know if my blower motor resistor is bad?

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 doesn't work at low speeds. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely.

Likewise, what causes heater resistors to burn out? 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 wires/plugs, heating up resistors shortening their life. Then they buy a aftermarket blower motor and again it keeps burning up.

Moreover, can you test a blower motor resistor?

Place one lead of the Ohmmeter on terminal 1 of the resistor. Place the other lead on terminal 2 and check against specifications. If this circuit is open, showing infinity on the Ohmmeter, the blower resistor must be replaced. Move the lead from terminal 2 to terminal 3 and check this reading against specifications.

Will a blower motor work without the resistor?

Power to the blower motor is fed through the blower motor resistor, so if it fails or has any issues power can be cut off to the motor. A blower motor without power will not be able to produce any air pressure, and as a result the heating and air conditioning system will be left with no air coming from the vents.

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How do you know if a resistor is bad?

Set a digital multimeter for "ohms." Set an ohms range that is equal to or higher than the value of the resistor to be tested. Touch the red lead from the meter to one side, and the black lead to the other. Resistors do not hold a polarity, so it doesn't matter which side gets the red or black lead.

What are the signs of a bad blower motor?

Symptoms of a Bad or Failing Heater Blower Motor
  • Weak airflow from the vents. One of the first symptoms of a potential problem with the vehicle's heater blower motor is low airflow from the vents.
  • Fan only blows at certain speeds. Another symptom of a bad or failing heater blower motor is a motor that only functions at certain speeds.
  • No air from the vents.

What is the blower motor resistor?

The blower motor resistor is an electrical component that is a part of the vehicle's heating and air conditioning system. It is responsible for controlling the blower motor's fan speed. A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system.

How much is a blower motor resistor?

The average cost for a blower motor resistor replacement is between $119 and $161. Labor costs are estimated between $47 and $60 while parts are priced between $72 and $101. Estimate does not include taxes and fees.

What can cause a blower motor to stop working?

In a situation where the motor doesn't work on any speed, the most likely causes are: a blown power supply fuse, a bad motor ground connection, bad motor speed control module or a failed motor. On all systems, a failed blower motor is least likely. Start by checking the blower fuse and HVAC controller fuse.

What is the difference between fan blower and compressor?

A blower is a machine used for moving gas with a moderate increase of pressure: a more powerful fan, if you will. A compressor is a machine for raising gas to a higher level of pressure, actually making the air denser by cramming air into a small space.

What happens when a resistor burns out?

When a resistor breaks down, current typically flows through the burnt resistor without any resistance and thereby passes unchecked. Other components in the circuit may become damaged from the excess current flowing through.

Is there a fuse for the heater blower?

The blower motor is powered by a fuse-like device called a relay. If your heater or air conditioner does not blow air through the vents, this could indicate that the blower motor fuse has probably blown. While replacement is easy, the exact location of your blower motor fuse may vary from vehicle to vehicle.

What happens when a blower motor resistor goes bad?

If you have faulty blower motor resistor you may experience low airflow coming from the vents even when the fan is all the way on high. In some cases bad blower motor resistor may not even turn the blower motor fan as a result your fan will not work at all and there will be no air coming from the vents.

Can you bypass a resistor?

A wire in the left circuit is shorting the 100Ω resistor. All current will bypass the resistor and travel through the short. The voltage across the 100Ω resistor is going to be zero. So typically the assumption of a short is done by redrawing the circuit.

How long do blower motor resistors 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.

What causes a resistor to fail?

A fixed composition resistor normally fails in an open configuration when overheated or overly stressed due to shock or vibration. Excessive humidity may cause an increase in resistance. A variable composition resistor may wear after extensive use, and worn away particles may cause high resistance short circuits.

Why does my blower motor work sometimes?

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. Blower resistors are small parts that can become corroded or just burn out, and a new one often costs less than $50.

Why does my heater only work on high?

If your heater only blows when the setting is on high, this may suggest that you have a faulty blower motor resistor. The highest speed setting may still work because in most cars in the highest fan speed settings the current bypasses the blower motor resistor.

How much does a blower motor cost?

The average cost for a blower motor replacement is between $363 and $394. Labor costs are estimated between $87 and $111 while parts are priced between $276 and $283. Estimate does not include taxes and fees.

Where is the blower motor resistor?

It's located inside the dash, often on the opposite side of the steering wheel or inside the engine compartment on the firewall. A blower motor resistor or a blower motor control module is the part that controls the speed of the blower motor.

How do you change a blower motor resistor?

Difficulty
  1. Remove the negative battery terminal.
  2. Locate the blower motor resistor on the passenger side under the dash board.
  3. Disconnect the electrical connector to the blower motor resistor.
  4. Remove the screws or bolts to the blower motor resistor and remove the resistor.
  5. Installation is the reverse of the removal.