Inducer Motor Guide

Inducer Motor Guide: Warning Signs, Troubleshooting and Replacing

An inducer motor is a motor-driven fan located in the top portion of the furnace box. The inducer motor moves air through the furnace and heating vent pipes. It has an electrical box for housing power connections and a metal housing.

Overall, the purpose of the motor is to move harmful gases, including carbon monoxide, out of your home. The inducer motor accomplishes this with its furnace vents or a chimney.

Of course, it is usual for things to go wrong sometimes. The health and property impacts of a faulty inducer motor can have horrible consequences. As such, this article includes a description of warning signs, a troubleshooting inducer motor guide, and detailed instructions on replacing your inducer motor.

At a Glance: Top Inducer Motors

07/20/2024 05:26 am GMT

How does a Furnace Inducer Motor Work?

Furnace Inducer Motor

Here is step-by-step information for understanding how the inducer motor works within a furnace, including its functions and processes.

  • Step One: The inducer motor turns on once the furnace begins its heating cycle.
  • Step Two: The inducer motor can discharge any combustion gases in the heat exchanger from the previous heating cycle. Your furnace does the discharging process by turning on the inducer motor before igniting its burners.
  • Step Three: The toxic gases are flushed into your system’s flue pipes and vented out of your home.
  • Step Four:  Once the burners ignite, the draft inducer continues to run to provide the burners with a constant source of oxygen.

Warning Signs your Inducer Motor is Not Working

Here are red flags that your inducer motor is bad or going bad:

  1. Humming noises: A humming noise from an electric motor is often a misaligned or bent shaft.
  2. Shrieking noise: This unpleasant sound is a warning of motor bearings wearing down.
  3. Grinding noise: Not a good sign; the motor might be burning out.

Inducer Motor Troubleshooting Guide

The troubleshooting guide below aims to help you better understand what can go wrong with the motor inducer, what repairs might help, and when to contact a trained professional.

Below are the top 7 possible problems:

Problem 1: Signal Error

Sometimes the signal wire from the thermostat doesn’t make its way back to the control board to inform the inducer motor to turn on. Here is how to confirm if the control board is receiving the signal back from the thermostat.

  • First, we have an R terminal (usually a red wire) connected to the thermostat’s W terminal on the inducer motor. Then the W comes back from the thermostat to the inducer motor as a 24-volt wire.
  • Have the multimeter set to volts AC, and with its negative terminal (usually black), place it on the inducer motor’s negative terminal (typically black or blue).
  • Using the positive terminal (usually red) from the multimeter, touch the rest of the terminals on the inducer motor to confirm the signal status. For example, if you check the thermostat wire and it reads zero, then in this case, there is either a problem with the thermostat itself or the thermostat wires; the same goes for the rest of the wires.

Interesting Read: How to Find the Best Furnace Control Boards.

Problem 2: Control Board Signal

Suppose you tried the above solution (Problem One) and verify that you have around 24-volts to 29-volts from the thermostat to the inducer motor, and it is still not working. In that case, it is time to move on to solution number two, considering inducer motor wiring.

  • First, ensure that you have the correct wire and trace it back to the control board from the inducer motor.
  • Now disconnect the wire, have the probes from the multimeter in the control board and check for voltage. Usually, the control board should be sending 120-volts to the inducer motor, but if it is not, there is a problem with the board.

Whenever you think it is a board problem, make sure you are not quick to blame the board. In most cases, one of the relays closes, thus not allowing the 120-volts to go through.

Or it could be the sensor, but if it happens to be the sensor, you will notice that the inducer motor blower cannot turn off or on. So make sure that the limit sensors work correctly.

If you have tried the above suggestions and there is still a problem with the board, look at the manufacturer’s troubleshooting guide for that model number.

Problem 3: Faulty Capacitor

If the inducer motor is still not working and you have a 120-volt or 240-volt inducer motor, your capacitor could be faulty.

A capacitor is a device that stores electric energy in the motor, and it has two conductors. It looks like a giant battery or a tiny box with two terminals, and it is usually shaped like a cuboid or a cylinder.

When it’s working correctly, the capacitor will send an electric energy surge to the inducer motor. When it’s not, the inducer motor also doesn’t work. Here is how to fix it:

  • Make sure the power is off, and then disconnect the two terminals.
  • Next, gently scrape the terminals of the capacitor to remove any particles that may interfere with its functioning.
  • Test the terminals with the multimeter; turn the multimeter to microfarads since we are testing the capacitance. Then check the readings after 15 seconds to ensure it is correct.

According to your inducer motor model, if the multimeter reads zero or anything below the average – you need to replace the capacitor with the appropriate size.

Furnace Inducer Motor

Problem 4: Compromised Inducer Motor Bearings

Bearing-related problems are one of the most common causes of inducer motor failures. For example, a bearing that is starting to rust can place an extra load on the motor. That extra load would then, in turn, cause the motor to draw excessive current.

  • If you suspect this may be the problem, you have to locate the induce motor shaft and gently spin it with a plyer or a tool of your choice. If it spins freely, then it is good – but if it does not, it needs to be either serviced or replaced. Do the same for every shaft in the motor, including the fan blower. Spin it with a screwdriver or any other object that can fit into the fan protector openings.
  • Also, the inducer motor has oil ports on it, although they are not sealed bearings, which means they will likely need to be lubricated. If it runs out of oil and the bearings are stiff, it is damaged, and you need replacements.

To add oil:

  • Put in the tiny hose mouth of a zoom sprout or any other oil container at your reach into the oil ports.
  • Put the hose mouth in the port, then squeeze the container until it’s overflowing but not too much.
  • Make sure you get enough oil to fill up the oil port. Finally, please make sure that you are putting the oil into the correct port. Do this by looking carefully for an oil trough.

Problem 5: Loose or Rusty Inducer Wheel

If the inducer wheel happens to be loose or rusty, it usually binds on the edge of the heat exchanger.

This state could obstruct the inducer motor from turning correctly. Or, something could be stuck in the wheel, which prevents the engine from turning on. In this case, the wheel either needs to be serviced, fixed, or replaced entirely.

Problem 6: Pressure Switch

If it is not of the above five problems, then it is time to check if the pressure switch is working correctly. The purpose of the pressure switch is to indicate that the inducer motor is working and there are no clogs. After that, the ignition source turns on. So, in this case, the problem could be that the pressure switch fails to indicate that the inducer motor is running. Here is what to do about it:

  • The first thing that you need to do is measure the pressure switch with a DMM 6 tool. With this tool, you can isolate the pressure switch away from the heating system to verify it is working correctly.
  • Next, disconnect and gently blow out, with your mouth, the tube lines. Butt make to disconnect the tube lines from the switch before putting any pressure on them.
  • Suppose the results of the tests are not reasonable. In that case, it is most likely that the tubes or drain piping are clogged. Alternatively, there may be a clog in either the exhaust or the intake of the heat exchanger. Still, if that is the case, it’s a dire situation which means a professional’s inspection is required.

Problem 7: The Main Inducer Motor

The final problem could be that the inducer motor has burned out due to overheating or other causes. Here is how to troubleshoot this problem:

  • Sniff the motor or the wires to detect if the windings are burnt. Make sure that the furnace is switched off, then using a multimeter, test the resistance. Be sure to unplug the motor and the capacitor.
  • First, check the ground wire, do not put the testing probe in the front; always put it from the back. With one probe on the ground wire, test for resistance values between ground and common wires.
  • Make sure you put the probe between the spade connector and the plastic, not into the spade connector itself.
  • If the multimeter reads 0.0 ohms, then the windings have me. If that is not the case, the situation is not dire. But if it is, then it is time to consult a professional.
probelm with Furnace Inducer Motor

How to Replace an Inducer Motor

Below are some instructions on how to replace your furnace’s inducer motor.

What you need to get started:

  • Draft inducer motor
  • Screwdriver or nut driver

Step 1: Disconnect the Furnace

Before getting started, make sure to shut off the furnace’s power. Also, close off the gas valve connected to it. Finally, remove the top cover panel, which exposes the inside of the furnace.

Step 2: Remove the Inducer Motor

First, disconnect the pressure hoses, then remove the wires. Both are connected to the inducer motor.

Then with a screwdriver or nut driver, unscrew and remove the pressure switches. Some furnaces will only have one, but if yours happen to have two, follow the same procedure as the first one.

Once the pressure switches are off, loosen the clamp and slide the exhaust pipe up. Once the exhaust pipe is off, disconnect the grounding (earth) wire and the draft inducer motor wire.

Finally, unscrew the mounting screws and then remove the inducer motor.

Step 3: Replace the Inducer

Some inducer motors need a ring to restrict flow that precisely matches the output of the furnace. If this is the case, install the disk.

Align the new motor, tighten the mounting screws, then reconnect the motor wires.

Now secure the grounding wire to the furnace housing, then carefully slide back in the exhaust pipe down and secure the clamp.

Align the pressure switches, tighten the screws with the screw or nut driver and reconnect the wires. Finally, attach the pressure switch hoses.

Step 4: Reconnect the Furnace

Replace the furnace’s upper cover, open the power valve, and turn on the power to the furnace. After doing this, your furnace should start running normally.

Buying an Inducer Motor

What factors should I consider when buying?

There are many factors to consider when looking for a replacement Inducer; these include:

  • Voltage;
  • Amperage;
  • Wattage;
  • Horsepower;
  • The vent pipe diameter; and,
  • Size of the cutout required for the motor.

Top Four Inducer Motor Brands

Below are some basic facts about the top inducer motor brands with a link to some reputable online sellers.

 A.O SmithYorkGoodmanDayton Grainger
Seller WebsiteHVACBrain, AmazonAmaze Supply, AmazonAMRE Supply, AmazonRadwell


Your inducer motor is a fan that pulls out the toxic frames (carbon monoxide) inside the furnace and vents them out of our homes. This indeed is a serious component of your furnace. Just like any other motor, it can last up 20 years if used properly. The main cause of the inducer motor going bad before its time is overheating and excess moisture. In the article above, you can see the installations and replacement, repair, and troubleshooting procedures.

FAQ (Frequently Asked Questions)

Question: What exactly does an inducer motor do?

Answer: An inducer motor pulls out the toxic air from the furnace and vents it out of your home.

Question: How do I know when my inducer motor is bad?

Answer: There could be more than one symptom, for example:
• A bad inducer motor can prevent the furnace from producing heat altogether.
• A bad inducer motor may create noises (humming, shrieking, or grinding) shortly after a heating cycle begins.

Question: Can a furnace use more than one inducer motor?

Answer: It is most unlikely and unnecessary since one inducer motor is good enough for one furnace.

Question: How long does an inducer motor last?

Answer: Just like any other motor, an inducer motor can last up to 20 years.

Question: Where can I buy an inducer motor?

Answer: You can purchase one from any of the brands mentioned above in this article on e-bay, Amazon, and other online stores.

Question: How much does an inducer motor cost?

Answer: The price range of an inducer motor can be from $85 to $1,150. However, the average price of a furnace inducer motor is between $245 and $465. If the broken part is under warranty, you should only pay for labor, which can be somewhere around $245. However, all of this depends on the manufacturer.

07/20/2024 05:26 am GMT


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