How To Check If Blower Motor Resistor Is Bad? new for 2022


How To Check If Blower Motor Resistor Is Bad?

Problems with a blower motor resistor are common in many cars. 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.Aug 1, 2021

How do I know if my blower motor resistor is bad?

Symptoms of a bad heater blower motor resistor
  1. Fan does not work at all, so no air comes out of the vents.
  2. Fan only works on some speeds and not others.
  3. Fan only works on the highest speed.
  4. Fan runs all the time and can’t be controlled with the fan switch.
  5. You see smoke coming out of the vents.

How do 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.

Can you bypass a blower motor resistor?

In the highest speed state, the blower resistor is bypassed completely and the fan is connected directly to the car’s battery, which allows maximum current through the motor. 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.

Can you fix a blower motor resistor?

What happens when blower resistor goes bad?

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.

Why does my blower motor resistor keeps melting?

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.

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What are the symptoms of a bad blower motor?

Here are just a few of the signs that your blower motor is going bad.
  • Weak airflow. This is one of the first signs of a bad blower motor that people tend to notice. …
  • Noises. Have you noticed any unusual noises coming from your vehicle’s HVAC system? …
  • Smoke or smells.

Why does my blower motor not work on high?

Blower works on slow speeds, but not on high speed

Check for bad fuse or bad high speed relay. Swap the high speed relay with another relay with the same part number. Also, check the fuse for the control side of the high speed relay. Make sure the ground side of the high speed relay is working.

How do you test a blower motor with a test light?

How do you bypass a blower motor on a furnace?

What does a blower relay do?

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 bypass a furnace blower motor relay?

How do I reset my blower motor?

How to Find and Reset your Furnace Motor Blower
  1. Step 1: Turn off the power to the furnace. …
  2. Step 2: Remove the blower compartment cover. …
  3. Step 3: Make sure the blower is completely cooled off. …
  4. Step 4: Locate the reset button. …
  5. Step 5: Press the button in (assuming that this is your issue and that the button has popped).

Why does my air conditioner in my car only work on high?

When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds, so the fan runs slower.

Why does my blower motor work sometimes?

The fan switch may be at fault, but a more likely reason is that a blower motor resistor that controls the voltage going to the blower has packed it in, resulting in only one speed remaining operable – usually the highest speed. …

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How do I test a resistor with a multimeter?

How do you know if a resistor is bad?

How to Know If Resistors Are Good or Bad
  1. Turn off the power running through the circuit containing the resistor you need to test. …
  2. Look at the color bands around the barrels of the components for the code to determine resistor values. …
  3. Check resistor values with the color codes.

Are blower motor resistors supposed to get hot?

This would be normal. Many blower motor resistors are designed such that they would burn up if they are not in the path of the air from the blower fan.

What would cause a resistor to burn up?

Burning of Resistor

When a resistor has been overloaded with voltage exceeding its power rating, the resistor will become very hot to touch, darken considerably and possibly even melt or catch on fire. … However, it may be functioning with less resistance than it was originally designed for.

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.

How do you test a blower motor with a multimeter?

Using a multimeter set on the Ohm scale, use the positive lead and test the black wire. To check the purple wire for current, use your ignition key and turn it to the run setting, turn the heater power to full power and set the multimeter to DC power. If your meter reads “no current” the motor is no good.

How do you troubleshoot a blower motor?

How do you test a blower motor on a car?

Why does my blower motor only work on low?

It sounds like this may be a sign of a faulty blower motor or bad wiring between the motor and the resistor. … The electrical contacts may also wear out causing the motor to fail. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your blower motor.

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How do you check blower voltage?

What is blower resistor?

The blower motor resistor is responsible for controlling the blower motor speed. In the past, this was done by varying the voltage supplied to the blower motor. … The change in resistance controls the current through the blower motor, which in turn limits the speed that the blower motor spins at.

How do you test a blower motor relay with a multimeter?

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.

How do you test a furnace blower relay?

How do you turn on a blower without a furnace?

The fan switch usually has two settings: auto and on. Switch the fan setting to “on,” instructs Fireplace Hubs. Listen for the sound of the blower turning on. Check that air is being sucked into the cold-air returns and being blown from the warm-air registers.

How do you access the control board on a furnace?

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.

Is there a fuse for 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 an air handler relay?

How do I know if my furnace circuit board is bad?

Common warnings signs that your furnace control board is bad include warning lights on your furnace’s diagnostic system (see step 1 below), temperature instability (significant fluctuations in temperature, especially when the thermostat is ok) and interruptions in the normal sequencing of your furnace.

Heat Stopped Working In My Car! Blower Motor or Resistor?

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