LG Furnace: Won't Start or Turn On
Commonly a faulty igniter, a dirty flame sensor, or a blower or control fault. Add a photo of your LG Furnace in the box below: the Triage Profile says what it is, how urgent it is, and who to call.
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In the next five minutes
Safe first steps, before the call. Nothing here needs a tool.
If you smell gas, a carbon monoxide alarm sounds, or anyone feels dizzy or sick: don’t touch any switch or plug, leave and get everyone out, then call 911 or the gas company from outside.
No gas smell? Switch the furnace off at the thermostat and at its breaker.
Don’t use it again until it’s checked, and keep people away from it.
Everything else about this problem
Is it an emergency?
Is an LG furnace that won't start an emergency?
Usually not, but it can be. Because this can be an emergency, leave it off and get it checked; don't reset it or turn it back on. Stop and call a pro if it keeps tripping the breaker, smells like burning, or you smell gas.
Symptoms & causes
Your LG furnace is completely unresponsive, showing no signs of power, no fan operation, and no heat production, indicating a total failure to initiate its startup sequence. This could stem from a tripped circuit breaker, a faulty thermostat sending no call for heat, or a safety lockout triggered by issues like a clogged filter or ignition failure. A dirty flame sensor or a malfunctioning pressure switch are common culprits that prevent the furnace from detecting a successful ignition or proper venting, leading to a complete shutdown.
Tools & parts
A digital multimeter is essential for checking voltage at the furnace and continuity of components like fuses and limit switches. A basic screwdriver set will be needed to access control panels and internal components for inspection and replacement. You might also need a new LG-compatible air filter and potentially a replacement flame sensor if cleaning doesn't resolve the issue.
Safety first
Always prioritize safety by first shutting off all electrical power to the LG furnace at the main circuit breaker and turning off the gas supply valve before attempting any inspection or repair. Be extremely cautious of potential electrical shock hazards from live wiring and the risk of gas leaks, which can lead to explosions or dangerous carbon monoxide buildup. Never bypass safety switches or interlocks, as they are critical components designed to prevent hazardous operating conditions and ensure safe furnace operation.
When to call a pro
A professional technician is required if your LG furnace's main control board (PCB) is faulty, often indicated by specific error codes that don't clear or a complete lack of power despite correct voltage input. Complex issues like a failed inducer motor, a malfunctioning pressure switch, or a cracked heat exchanger demand specialized testing tools and expertise for safe and effective repair. Persistent gas valve failures or ignition problems after basic troubleshooting also necessitate a certified technician to ensure proper gas flow and combustion safety.
Questions people ask
Why is my LG furnace not turning on after a power outage?
After a power outage, your LG furnace might be in a lockout mode or the circuit breaker could be tripped. Check your home's electrical panel for a tripped breaker and reset it, then try resetting the furnace by turning the thermostat off and on.
What does a flashing light on my LG furnace mean when it won't start?
A flashing light on your LG furnace is typically an error code indicating a specific issue. Consult your LG furnace owner's manual to decipher the code, which often points to problems like a dirty flame sensor, pressure switch failure, or ignition lockout.
Can a dirty air filter prevent my LG furnace from starting?
Yes, a severely clogged air filter can restrict airflow, causing your LG furnace to overheat and trigger a safety limit switch, preventing it from starting. Replace the filter with a clean one to restore proper airflow and allow the furnace to operate.
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What it is, how urgent, who to call
Add a photo of your LG Furnace in the box at the top. The Triage Profile says what it is, how urgent it is, and who to call.