What is a common, straightforward diagnostic step when diagnosing furnace ignition problems?

What is a common, straightforward diagnostic step when diagnosing furnace ignition problems?

• A. Faulty or dirty ignition/igniter; check for proper flame signal or spark, and verify gas valve operation and wiring continuity.
• B. Ignore the ignition system and wait for it to fix itself.
• C. Replace the thermostat without testing ignition.
• D. Disconnect power and ignore safety precautions.

Answer: (A)

Diagnosing furnace ignition problems starts with examining the ignition path itself. A common, straightforward step is to inspect the ignition/igniter for faults or dirt, verify that it is producing a spark or that the flame sensor is reading a flame, and confirm the gas valve is receiving the control signal and that the wiring to the ignition and valve is continuous. If the igniter is dirty or damaged, or the flame signal isn’t detected, the furnace won’t light even when gas is present. Checking the gas valve operation and wiring continuity helps determine whether the issue lies in the ignition hardware or the control circuits. This approach is more direct and actionable than options like ignoring the ignition system, replacing the thermostat without testing ignition, or disconnecting power without following safety procedures.

Diagnosing furnace ignition problems starts with examining the ignition path itself. A common, straightforward step is to inspect the ignition/igniter for faults or dirt, verify that it is producing a spark or that the flame sensor is reading a flame, and confirm the gas valve is receiving the control signal and that the wiring to the ignition and valve is continuous. If the igniter is dirty or damaged, or the flame signal isn’t detected, the furnace won’t light even when gas is present. Checking the gas valve operation and wiring continuity helps determine whether the issue lies in the ignition hardware or the control circuits. This approach is more direct and actionable than options like ignoring the ignition system, replacing the thermostat without testing ignition, or disconnecting power without following safety procedures.