How to Check a Furnace Blower Motor

A blower motor is a crucial component in your heating and cooling system. And, a failing blower motor during the cold season isn’t something you want. It can turn your comfortable home into a freezing zone.

Generally, like any other moving part of your HVAC system, this vital component is prone to the effects of wear and tear. Therefore, if you find out that your system is not blowing warm air into the house, you better check your blower motor.

Issues with furnace blower motors can range from simple ones that you can sort yourself to complex ones that need an HVAC technician. It’s, therefore, paramount to be able to identify the problem in your blower motor to determine your next course of action.

Luckily, testing a blower motor isn’t a complex task. So, with our guide on how to check the blower motor, you’ll be good to go. 

Signs that Indicate a Failing Blower Motor

Before the furnace blower motor stops functioning completely, there must be signs that precede the breakdown. Some of these signs can be noticed without closely paying attention, while others require a keen eye for detail.

The following are the signs common to a failing furnace blower motor.

  1. Weak Airflow

Undoubtedly you can differentiate between a strong or weak airflow coming out from your vents. Can’t you? If it’s weak, then it’s an early sign showing a blower motor that is about to break down.

Weak airflow reveals that the motor is stressing to blow adequate air as required, and soon, the motor will become weaker and eventually stop working altogether.

Dust and dirt are major culprits in weakening the blower motor. They add resistance to the rotating part of the motor, the reason why you should ensure the motor stays clean. Also, the motors get weary with time, as they have a lifespan too, and will require you to get a new one, eventually.

  1. No Airflow from the Vents

If no air is coming out of the vents, it means that the motor has completely malfunctioned. Also, the thermostat could be the root problem to this as it controls the HVAC System. It is advisable to also check the fan and the batteries.

  1. Electricity Bills Inexplicably Rising Up

In the whole HVAC system, the motor consumes the highest energy. There have been many cases of individuals complaining that they don’t understand how their electricity bills rise so high.

Well, an old motor or one with dirt will lead to a spike in electricity bills, as the motor tends to work harder to provide the required circulation of air. This will cause the motor to consume more energy than usual.

In this case, it’s advisable to get yourself the new model AC Unit, which is programmable. This will help vary the furnace blower motor speed according to temperature change in your house.

  1. Strange Sounds from the HVAC Unit

Did you hear any sound other than the warm or cold air being smoothly blown out from the vents? If yes, contact an HVAC professional to come and lubricate the belts and bearings of the blower motor.

Otherwise, if assumed, the system may crash completely, requiring you to replace it with a new system. And this can be quite costly.

  1. Overheating

Upon noticing your HVAC System overheats on various occasions, take action immediately. Contact a professional to handle your case because overheating is undoubtedly risky to homesteads. High temperatures are likely to start up a fire that can cause serious damage.

But what may make your HVAC System overheat? You can confirm with a technician if the motor installed in your cooling and heating system is up to its task. A small motor, required to perform a bigger task, will overheat as it strives to blow enough air.

How to Test a Furnace Blower Motor: Key Steps

After you’ve learned the crucial signs that a failing furnace blower motor displays, it’s now time to learn how to test it. And, as mentioned earlier, testing a blower motor isn’t too complicated.

In fact, if you have the right tools (the non-contact voltage tester and a multimeter), the rest is easy. Follow these simple steps to test a furnace blower motor;

1. Turn off the Power to the Furnace

Safety measures should be taken seriously, ensure to switch off the power to the furnace blower motor. If you have a power furnace switch, do it from there. Also, you can turn the power off from your breaker inside the Consumer Control Unit.

2. Take off the Furnace Access Panels

Open the casing covering the Furnace blower motor to expose the inside structure. This will help you troubleshoot the reasons why your motor is failing or malfunctioning.

3. Test the Continuity of the Motor Circuit

The next step is to check if there is any visibly damaged fan or shaft. Then, with the help of a multimeter tune, test continuity from the two wires taking electric current to the motor. Connect the multimeter’s red and black wires to the positive and black terminal, respectively.

A complete circuit should have small values indicating very minimal resistance from the positive to the negative terminal. An incomplete circuit will have very high resistance values indicating the circuit is not complete.

4. Test the Thermostat

The furnace blower motor relies upon the signals from the thermostat. This implies if you have a faulty thermostat, your blower motor cannot function.

For a programmable thermostat, check temperatures adjustments and tune them according to the exact temperature in the room.

5. Checking the Motor Windings

Using a thermostat, adjust it to test for resistance. The windings act as electromagnets to provide a magnetic effect inside the motor. Any wire in the winding which is broken will stop the motor from functioning.

The winding has terminals A and B. And on these terminals, you will test the resistance across the windings.

For a complete winding without any broken wire, the readings will be small. However, if it reads infinity values, there is an opening in the winding.

6. Checking the Capacitor

The term capacitor may be common, but many people do not know how this component actually works. Especially in your furnace blower motor. Capacitors stores electric energy, and in this case, that energy is responsible for providing the necessary torque to run the motor.

Therefore, if the capacitor is faulty, the furnace blower motor will not function properly.

By learning how to check a blower motor and taking the necessary action, you’ll have ensured that the winter doesn’t get the best of you. 

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