Inducer Motor Problems: How to Diagnose and Replace
The inducer motor is the first thing that kicks on when your furnace starts a heating cycle. It’s a small blower that pulls air through the heat exchanger and vents combustion gases out through the flue pipe. If the inducer motor doesn’t run — or doesn’t run fast enough — your furnace will lock out before the burners ever light.
What Happens During a Normal Startup
Here’s the sequence: the thermostat calls for heat, the control board sends power to the inducer motor, the inducer spins up and creates draft, the pressure switch closes to confirm draft, and THEN the ignitor heats up and the gas valve opens. If the inducer fails at step two, nothing else happens.
Signs of a Bad Inducer Motor
Loud rumbling or rattling on startup. A healthy inducer makes a steady hum. If it sounds like a washing machine with an off-balance load, the motor bearings are worn.
Furnace starts then locks out. If the inducer runs but can’t create enough draft, the pressure switch won’t close. The board tries a few times, then locks out. You might see a blinking LED code on the board — often 2 or 3 blinks for pressure switch fault.
Burning smell. A motor with seized or failing bearings draws excessive current and overheats. You may smell burning before it fails completely.
No sound at all when the furnace tries to start. If the thermostat calls for heat and you hear nothing from the furnace, the inducer motor (or the control board sending power to it) may have failed.
Testing the Inducer Motor
First, verify power is reaching the motor. With the thermostat calling for heat, use a multimeter to check for 120V at the inducer motor connector. If you have voltage but the motor isn’t spinning, the motor is bad. If you have no voltage, the problem is upstream — likely the control board or a safety switch.
You can also check the motor windings with an ohm meter. Disconnect the motor leads and measure resistance across the windings. An open reading (infinite ohms) means the winding is burned open. A very low reading (near zero) could mean a shorted winding.
Replacing an Inducer Motor
Inducer motors are specific to your furnace model because the housing shape and mounting pattern must match. The motor number is usually on a label on the motor itself. Bring the whole assembly in if possible — that makes matching much easier.
Open To Public HVAC Parts stocks inducer motors and assemblies for Goodman, Rheem, Carrier, Trane, and Lennox. Walk in with your old motor and we’ll cross-reference it. Free testing at the counter. 510+ Google reviews. Since 1998.
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