Won't Turn On in Spokane, WA

A furnace that won't start has to fail somewhere in a specific sequence. Understanding that sequence helps you understand why diagnosis matters.

Here's how a furnace start cycle works - and where it can break down:

1. Thermostat or wiring issues The call for heat starts at the thermostat. A dead battery, a misconfigured setting, or a wiring fault between the thermostat and the furnace control board can stop the cycle before it ever begins.

2. Control board failure The control board is the brain of the furnace. It receives the thermostat signal and sequences every component in order. A failed board - or a board in lockout mode from repeated failed start attempts - won't initiate the cycle.

3. Inducer motor not running Before the burners fire, the inducer motor (a small fan that clears combustion gases from the heat exchanger) has to spin up and prove it's running. If the inducer motor fails or runs slowly, the furnace won't proceed.

4. Pressure switch failure The pressure switch confirms that the inducer motor is creating the right airflow. It's a small, inexpensive part - but it fails more often than people expect, especially in furnaces that are 10–15 years old. Spokane has seen a significant building boom over the past 15–20 years, and a lot of those builder-grade units are now hitting the age range where pressure switches, ignitors, and flame sensors start to go.

5. Ignitor failure The hot surface ignitor glows to ignite the gas. Ignitors are fragile and wear out over time. A cracked or burned-out ignitor means no ignition - and no heat.

6. Flame sensor fouled or failed After ignition, the flame sensor confirms that a flame is actually present. A dirty or failed flame sensor will cause the furnace to light briefly, then shut back down - sometimes so fast you don't even notice it tried.

7. Safety switch trips High-limit switches, rollout switches, and pressure switches all exist to shut the furnace down if something is wrong. A tripped safety switch is a symptom, not a root cause. The root cause is whatever triggered the trip.

8. Gas supply issues If the gas valve isn't opening - or if there's an issue with gas supply to the home - the furnace won't fire. This is less common but worth checking.

Before you call, run through these checks. They take five minutes and sometimes solve the problem.

• Check the thermostat. Make sure it's set to "Heat" and the temperature is set above the current room temperature. Replace the batteries if it's been more than a year.
• Check the circuit breaker. Find your electrical panel and look for a tripped breaker labeled "furnace" or "air handler." Reset it once if it's tripped. If it trips again, stop - call us.
• Check the furnace power switch. There's usually a standard light-switch-style switch on or near the furnace. Make sure it's in the "on" position. It gets bumped off more often than you'd think.
• Check the furnace filter. A severely clogged filter can cause the furnace to overheat and trip a high-limit safety switch. Pull the filter and check it. If it's packed with dust, replace it and try again.
• Check the furnace door panel. Most furnaces have a safety switch that prevents operation if the access panel is open or not fully seated. Make sure the panel is closed and latched.
• Look for an error code. Many modern furnaces have a small LED light on the control board that flashes an error code. Count the flashes and check the legend - usually printed on the inside of the furnace door.

If none of these solve it, it's time for a professional diagnosis.