What to Do If You Hear Clicking in Your Furnace After a Storm in St. Louis

If you hear a clicking noise in your furnace right after a storm, first switch off the furnace power and gas supply, then wait for any moisture to evaporate. Once it’s dry, restore power and test it. If the clicking continues, moisture, debris, or a misaligned ignition sequence is likely the cause, and you should contact a trained HVAC technician.

 

Why Furnaces Click After a Storm

 

A furnace clicking after heavy rain, wind or lightning can occur because:

• Moisture from rain or humidity has seeped into electrical components.
• Debris, like leaves or twigs, was blown into the furnace vents during the storm.
• A power surge or brief outage disrupted the ignition control board or transformer.
• The flame sensor or ignition electrodes have become misaligned or dirty.

 

Immediate Safety Steps to Take

 

Before inspecting or touching any part of the furnace, follow these safety steps:

• Locate the furnace’s power switch or circuit breaker and turn it off.
• If your furnace has a manual gas shutoff, switch the gas valve to “Off.”
• Avoid standing water; wear rubber gloves and boots if the area is damp.
• Keep children and pets away from the furnace while you troubleshoot.

 

Inspecting for Water and Debris

 

Storms can force water or debris into your system. Check the following:

• Exhaust and intake vents outside: clear away leaves, twigs, or mud.
• Vent pipe joints: ensure they remain sealed and show no cracks.
• Drain pan and condensate line (for high-efficiency furnaces): remove standing water.
• Control panel area inside the furnace: look for drips or damp spots around wiring and circuit boards.

 

Checking the Ignition System and Flame Sensor

 

A clicking sound often comes from the ignition assembly trying to light the burner:

• Locate the ignitor or spark electrodes: these create the spark you hear clicking.
• Carefully wipe the flame sensor rod with a clean, lint-free cloth to remove corrosion.
• Ensure the spark gap (space between electrodes) matches the manufacturer’s specification (usually 1/8 inch).
• If you see visible cracks on the ignitor or electrode, they may need replacement.

 

Drying Out Furnace Components

 

Even minimal moisture can cause malfunction. To dry:

• Leave the furnace power off and let the area air-dry for several hours.
• Use a fan nearby to improve air circulation around the furnace cabinet.
• For hard-to-reach spots, a hair dryer on low heat can speed up drying—keep it at least one foot away.
• Once everything is dry, restore gas and power, then run a test cycle.

 

When to Call a Professional

 

If you’ve followed all the steps and clicking persists, get expert help. Especially if:

• Moisture has reached the control board or transformer—you smell burning plastic or see scorch marks.
• Ignitor or flame sensor replacement is needed but you’re not comfortable handling gas or electrical parts.
• The furnace repeatedly fails to light, cycles on and off rapidly, or trips safety switches.
• You live in St. Louis or Nashville and need same-day assistance to restore safe heating.

A qualified HVAC technician will perform a full system check, repair or replace damaged parts, and ensure your furnace operates safely and efficiently after storm damage.