Furnace Inducer Motor Troubleshooting

Inducer motors are responsible for powering the fan that brings combustion gases out of the heat exchanger. If the inducer stops working properly, your furnace will shut down and stop producing heat. By understanding how furnace inducer motor troubleshooting works and when to call Elkhorn Heating, Air Conditioning, Plumbing & Electrical for help, you can keep your family warm this fall and winter.

Quick Answer: What to Do Following a Noisy or Stalled Startup

The small motor noise you hear before the furnace starts is the inducer motor. If the inducer motor isn’t working properly, you may hear repeated clicks, or it may stall. A seized motor may also cause humming, grinding, or squealing noises. 

While unusual noises or a stalled startup don’t definitively mean that the inducer motor has stopped functioning, it is a possibility. By understanding what to look for and how to troubleshoot your inducer motor, you can narrow down the likely cause and determine when professional help is needed.

Where the Inducer Fits in the Heating Sequence 

When your thermostat senses that your home’s temperature has fallen too much, a heating sequence begins. Because each component plays a different role, you can narrow down potential problems with your unit by noting the symptoms.

How the Heating Sequence Works

The inducer plays an integral role in this process. If it isn’t functioning properly, your furnace won’t start.

• The Call for Heat: When the thermostat detects that your home’s air temperature has fallen enough, it sends a call for heat to the furnace control board.
• Inducer and Draft Checks: Once the call is received, the inducer motor is turned on to remove exhaust gases and ensure enough draft. The control board verifies that the draft pressure switch closes. This step is essential for ensuring your unit is safe enough to operate.
• Ignition and Flame Confirmation: After the draft check is complete, the gas valve opens and the igniter lights the burners. The flame sensor confirms that the burners have lit. If the flame sensor does not detect a flame, the control board will shut off the gas supply.
• Indoor Blower: Air is warmed up in the heat exchanger. After a preset delay that allows the heat exchanger to warm up, the blower motor turns on. Then, the blower sends the heated air through your ductwork and into your home.

Each Component Plays a Different Role

Your inducer, circulation blower, and draft pressure switch all play important roles in heating your home. The switch is designed to monitor pressure. If you see a switch fault code, it doesn’t automatically mean that there is a bad switch or motor.

• Inducer Motor: The inducer motor creates the draft needed to draw combustion air into the furnace and move combustion gases through the exhaust vent.
• Circulation Blower: Your circulation blower is designed to push heated air into your home.
• Draft Pressure Switch: This switch responds to the pressure differential created by the inducer. If the switch does not close, the ignition process immediately stops.

Symptoms to Pay Attention To

There are a few symptoms that you may notice that indicate your furnace inducer motor is not running properly. For your safety, you should never remove a cover to check the inducer yourself.

• No Inducer Sound: This can occur if the thermostat isn’t calling for heat, or the control board is unresponsive. It may also happen if your furnace lacks power, such as a tripped breaker.
• Humming or Rattling: These noises may indicate a failed motor or faulty fan blade.
• Inducer Operation Without Ignition: This symptom can occur if the pressure switch isn’t closing.
• Repeated Attempts: If the furnace repeatedly attempts to start without ignition occurring, it may be due to a problem with the igniter or flame sensor.

Why Inducer Motors Fail and What Can Mimic Failure

If the inducer motor fails, your furnace’s safety controls will stop the furnace from lighting. As part of your furnace inducer motor troubleshooting, it’s important to look at which symptoms occur. There are a few components that can produce similar symptoms to an inducer failure, which is why professional furnace repairs are essential.

Key Reasons an Inducer Fails

So, why do inducer motors fail? The following three issues tend to be responsible for most inducer motor failures.

Wear or Damage in the Motor or Fan Assembly

If the motor or fan assembly is worn, you may notice screeching or rattling noises whenever the furnace calls for heat. A seized shaft will prevent the motor from spinning.

The technician can confirm the issue by inspecting for cracks in the housing, manually spinning the blade, and looking at the internal bearings. If any of these problems are at fault, the inducer motor assembly will likely need to be replaced.

Moisture or Corrosion

Ongoing moisture can result in corrosion. When this occurs, you may notice a burning or electrical odor and scraping noises. You may also notice that the inducer produces a humming noise as it runs, but it doesn’t rotate.

In this situation, the technician will visually inspect the housing for signs of rust or scale buildup. They may also test the motor windings for short circuits. If moisture or corrosion is the cause of your problems, the affected component will likely be replaced. Then, the unit’s venting and drainage will be adjusted to prevent future moisture intrusion.

Power and Control Faults

If the inducer motor remains motionless when the thermostat and control panel call for heat, it may be due to an issue with the power supply or controls. Before calling a technician, it is a good idea to see if there is a tripped breaker preventing the unit from starting up.

Once one of our Comfort Specialists arrives at your home, we will verify the line voltage during the startup sequence. We will also measure your capacitor’s capacitance in microfarads if your unit has one. Then, we will repair or replace the affected electrical components, such as your wiring harness, control board, or capacitor.

Causes That Can Mimic an Inducer Failure

Because other symptoms can mimic an inducer failure, it’s important to pay attention to the following issues.

Blocked or Incorrectly Performing Venting

If the vent is blocked or damaged, you may notice that the inducer runs, but the furnace will not ignite. Often, this will also produce a switch fault code. In some cases, ignition will still happen, but the furnace’s operations will be affected.

Our Comfort Specialists can diagnose this issue by using a camera to detect blockages and visually inspecting your venting. Then, we can clear the vent and adjust the piping as needed.

Drainage Issues on Condensing Equipment

When there are drainage issues involved, you may hear a sloshing or gurgling noise when the motor starts. If water pools inside the inducer’s housing, it may stall.

We can detect this issue by inspecting your drain lines, condensate trap, and collector box for blockages and damage. Once we’ve diagnosed the issue, we can clear the blockage and repair damaged components.

Pressure-Sensing Faults

With pressure-sensing faults, the inducer may continue running, but the furnace may not proceed to ignition. We use a manometer to measure the pressure differential and determine whether the pressure switch is operating correctly. Additionally, we will check the inducer’s housing and tubing for cracks and damage.

Depending on the problem, our solution can vary. For example, we may need to replace the tube or pressure switch. Alternatively, our team may be able to fix the issue by cleaning the safety switch.

Ignition Faults After Draft Is Established

In this situation, you will hear the inducer motor start and stay on without a problem. However, the furnace never clicks, glows, or produces a flame. 

Our team will verify that the pressure switch, ignition sequence, and draft are all functioning correctly. In many cases, the main fix for this type of problem is replacing the ignition system component responsible for the malfunction.

What You Can Safely Check

As a homeowner, there are a few basic furnace inducer motor troubleshooting steps you can use to resolve the issue. If the following tips do not work, you should reach out for professional repairs.

• Confirm the Call for Heat: First, check the thermostat to see if it is actively calling for heat.
• Check the Thermostat Schedule: Then, verify that the thermostat is set to “heat” mode and a setpoint that is above the air temperature.
• Note Unusual Sounds or Codes: Pay attention to any unusual symptoms, such as odd draft inducer motor noises or error codes. Note any changes in the startup sequence.
• Observe the Vent Outlets: Check the exterior vent outlets from ground level to see if there are any issues. However, you should never dismantle or probe the outlets yourself. 

Important Safety Note: You should never open cabinet panels or spin a fan by hand. Do not directly energize the motor. You should also never jump switches, disconnect tubing, or test live terminals. If the furnace keeps locking out, do not repeatedly reset it.

When to Call for Professional Help

If you are concerned about your furnace draft motor in Denver, our Comfort Specialists can help. Once we come to your home, we can determine the underlying cause and walk you through the best solution. You should always reach out for professional help if you experience any of the following situations.

• Your home is persistently without heat.
• The furnace keeps overheating.
• There is a scraping noise.
• Your furnace experiences recurrent lockouts.
• There is a gas odor or the carbon monoxide (CO) alarm goes off. If this occurs, immediately evacuate the area and call your gas utility provider or emergency services for help. Afterward, you can call our team for repairs.

When we come to your home, we will verify that the system is calling for heat and the power supply is working. We will check the draft, condensate management, venting, pressure-sensing components, and drainage. Depending on the cause, the repairs needed can vary from fixing the drainage and venting to replacing the inducer motor.

How to Prevent Repeat Problems and Evaluate Your Repair Options

Our team is on hand to help with emergency furnace repairs. Once we’ve fixed your current issue, there are a few steps you can take to prevent furnace problems in the future.

The most important step is to schedule routine maintenance tune-ups. Our team can check your venting, drainage, and combustion for signs of an issue. In addition to preventing issues, our tune-ups can help you detect small, easy-to-repair problems before they escalate. With our Comfort Club membership, we make it simple to schedule routine maintenance.

If you notice an unusual noise or symptom, you should report it right away. Early detection and proactive repairs can prevent more complicated, costly repairs in the future.

Even with the best care and maintenance, furnaces will eventually break down once they reach the end of their lifespan. Our team can help you evaluate the costs and benefits of repairing or replacing your system. For example, your warranty coverage, the age of your system, its current condition, and the cost of repairs play a major role in determining whether a repair or replacement will make more sense.

Frequently Asked Questions

Is the inducer the same as the blower motor?

No, the blower motor powers the blower fan and circulates air into your rooms. The inducer is responsible for moving combustion gases out of your home through the exhaust vent.

Why does the inducer run without the burners lighting?

The inducer may run without the burner lighting if there is an issue with ignition, draft proving, or the controls. Even though it is able to run, it may not have satisfied all of the draft requirements.

Does a pressure-switch code mean the inducer failed?

No. A pressure-switch fault code appears when the control board detects that the pressure switch is not in its expected state during the heating sequence. You will need to schedule professional diagnostics to determine the model-specific cause.

Can I lubricate or reset a noisy inducer?

Do not lubricate or reset a noisy inducer. Follow the recommendations in your manual. Many of these assemblies are not intended to be serviced by homeowners, so you should schedule an inspection to address a noisy inducer.

Reach Out for Furnace Diagnostic and Repair Services

If your furnace isn’t working properly, our Comfort Specialists can help with furnace inducer motor troubleshooting. We offer prompt furnace repairs, flexible financing, and maintenance tune-ups in the Denver and Littleton area.

Schedule your next furnace repair today.