How to test and replace the blower motor on an electric furnace

Having trouble with your electric furnace not pushing warm air like it used to? The blower motor might be acting up. But no worries. You can test it and replace it yourself with a bit of guidance. Let’s walk through the steps to get your furnace back in action.

Important: This info might not match your specific furnace model exactly. We aim to provide helpful DIY repair advice, but different models can have varying troubleshooting steps, error codes, and parts. For the best guidance, check your manufacturer’s documentation for your model, or contact us if you’ve got any questions.

Safety precautions

When working on any appliance, remember to keep safety first. Here are some tips to keep in mind: 

• Always power off and unplug your appliance or switch off the circuit breaker before attempting any maintenance or replacement work. This keeps you safe by preventing any risk of injury from electric shock.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with bare wet hands. Make sure the work area is completely dry.
• Check your user manual to see if there are specific installation or safety instructions for your part or appliance. 
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• If the appliance has recently been used, give it plenty of time for any heating parts to cool down before working on it. 
• Take pictures or make a note of wiring terminals or other connections before disconnecting to prevent any problems with reassembly.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.

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How to test the blower motor

Before swapping out the blower motor, let’s make sure it’s actually the culprit. Here’s how to test it:

1. Perform a visual inspection

Sometimes, you can spot the problem just by looking.

1. First off, turn off the furnace’s power at the breaker to stay safe.
2. Check out the blower motor and nearby parts for any obvious signs of trouble, burn marks, scorch marks, or melted wires.
3. Look for any debris or obstructions stopping the blower wheel from spinning freely.
4. If you see any damage, you’ll need to repair or replace those parts.

2. Check power supply

Next, we need to see if the blower motor’s getting power.

1. Keep the power off for safety.
2. Set your multimeter to the right voltage setting for your furnace (usually 120V or 240V AC).
3. Carefully turn the power back on.
4. Check if the blower motor’s getting voltage by placing the multimeter probes on the right terminals while the furnace is calling for heat.
5. If there’s no voltage when there should be, the issue might be with the power supply or control circuit, not the motor.
6. After testing, turn the power off again.

3. Test capacitor

The capacitor helps the blower motor start and run. If it’s faulty, the motor might not work right.

1. Make sure the power’s off.
2. Find the capacitor connected to the blower motor, it usually looks like a small metal or plastic cylinder.
3. Discharge the capacitor by placing a screwdriver with an insulated handle across its terminals.
4. Set your multimeter to measure capacitance.
5. Connect the multimeter probes to the capacitor terminals.
6. Compare the reading to what’s marked on the capacitor. If it’s way lower, the capacitor’s bad and needs replacing.

4. Test relay

The relay controls power to the blower motor. Let’s check if it’s working right.

1. With the power still off, find the relay connected to the blower motor circuit.
2. Set your multimeter to the resistance (ohms) setting.
3. Measure the resistance across the relay’s coil terminals. Check the relay’s documentation for expected values. If you get infinite or zero resistance, the coil’s faulty.
4. Next, check the continuity of the relay contacts. Place the multimeter probes on the common (COM) and normally open (NO) terminals.
5. Apply control voltage to the relay coil (if it’s safe to do so). When the relay’s energized, there should be continuity between the COM and NO terminals.
6. If the relay doesn’t switch properly or the readings are off, it might be malfunctioning.

If after all that you find the blower motor’s faulty, it’s time to replace it.

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Replace the blower motor

1. Start by turning off the power to the furnace at the breaker or disconnecting the switch to ensure safety.
2. Find the panel covering the blower motor, usually on the front or side of the furnace. Remove any screws or clips holding the panel in place.
3. Label or take a photo of the wires connected to the motor to ensure correct reconnection. Carefully disconnect the wires using needle-nose pliers if necessary.
4. Locate and remove the screws or bolts securing the motor housing (blower assembly) to the furnace. Gently slide the blower assembly out of the furnace.
5. Loosen the set screw on the blower wheel and carefully remove the motor from the blower wheel and housing. If the motor is stuck, use a hub puller to free it.
6. Carefully disconnect the capacitor, remembering that it may still hold a charge. Discharge it safely by placing a screwdriver across the terminals while holding the insulated handle.
7. Compare the new motor to the old one to ensure compatibility. Insert the new motor into the blower wheel and secure it with the set screw.
8. Reconnect the wires to the new motor, using your labels or photos as a guide. Reconnect the capacitor and ensure all connections are tight.
9. Slide the blower assembly back into place, securing it with screws or bolts. Replace the access panel and secure it. Restore power, turn on the furnace, and check the blower motor for smooth operation without any strange noises or vibrations.

Read more: 12 simple space heater safety tips for this winter

Wrapping up

By following these steps, you can confidently test and replace the blower motor in your electric furnace. Taking on this DIY project not only saves you money but also gives you the satisfaction of fixing something yourself. Remember, regular maintenance can prevent many issues, so keep an eye on your furnace throughout the heating season.

Need parts or more guidance? Visit AppliancePartsPros.com for quality parts and expert advice. We’re here to support all your DIY appliance repair needs.

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