Mike PleziaInside service technician at Clark Associates

The Inducer: Where the Heat Starts

21 Oct 2026 · 1 min

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In this short instructional video, HVAC technician Mike Plezia explains to new tradespeople why the furnace inducer motor is the critical first component in the heating cycle. He describes how the inducer spins up before the igniter glows and the gas valve opens, creating the necessary draft to pull combustion gases through the heat exchanger and out the flue. If the inducer fails or runs slowly, the pressure switch will not close, causing the furnace to lock out and resulting in a no‑heat call. Plezia points out a common mistake among new techs: replacing the pressure switch without first verifying that the inducer is moving sufficient air. He advises a systematic check—listen for the motor, feel for suction at the pressure port, and inspect the inducer wheel for debris or motor bearings for wear—before swapping the pressure switch. The video’s goal is to shift diagnostic focus to the inducer, helping technicians troubleshoot more effectively and avoid unnecessary part replacements.

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Hey! Are you new to the trades? Here's something you may not know about the inducer motor and why it matters more than most new techs realize. The inducer is the first thing that runs in the furnace sequence. Before the igniter glows, before the gas valve opens, the inducer motor has to spin up and prove draft. It pulls combustion gases through the heat exchanger and pushes them out the flue. When the inducer fails or slows down, the pressure switch won't close, the furnace locks out, and you get a no heat call. But here's what trips up new techs. They replace the pressure switch without ever checking whether the inducer is actually moving enough air. On every pressure switch fault, check the inducer first. Listen for the motor. Feel for suction at the pressure port. If the inducer wheel is coated with debris or the motor bearings are going, no pressure switch will fix that. Start at the beginning of the sequence. The inducer is where the heat starts. Now that you know, you can help someone else know.