American Standard Furnace 5 Flashes: What It Means & How to Fix It
Compiled & reviewed by the HVAC Flash Codes editorial team · Updated 2026-08-28 · confidence: high
⛔ Stop — call a licensed pro
What does American Standard furnace 5 flashes mean?
Open limit or rollout switch — a high-temperature limit or flame-rollout safety switch has opened, indicating overheating or flame rollout. Most often caused by Low airflow from a dirty filter, blocked returns, or a dirty blower wheel.
What your furnace LED does. The diagnostic light blinks 5 flashes, pause, repeat — that pattern is American Standard furnace 5 flashes.
What American Standard furnace 5 flashes means
Open limit or rollout switch — a high-temperature limit or flame-rollout safety switch has opened, indicating overheating or flame rollout.
Common causes
Low airflow from a dirty filter, blocked returns, or a dirty blower wheel
Blocked or restricted flue causing overheating
Over-firing / outlet gas pressure set too high (pro adjustment)
Failed limit or rollout switch
Homeowner-safe steps to try
Replace or clean the air filter immediately — restricted airflow is the most common cause
Make sure all supply and return vents are fully open and unobstructed
Let the furnace cool, then power-cycle once at the breaker
When to call a licensed HVAC technician
If the basic checks below don't clear the code, the fault recurs, or anything involves the gas valve, burners, flame sensor or wiring, stop and book a licensed HVAC technician. Repairs to the combustion or gas system are not DIY.
⚠️ Safety first. Gas furnaces burn fuel and produce combustion gases. If you ever smell gas (a rotten-egg or sulfur odor), hear hissing, or your carbon-monoxide alarm sounds, do not touch light switches, thermostats, or the furnace — leave the home immediately and call your gas utility's emergency line or 911 from outside. Homeowners should limit themselves to simple, safe steps: setting the thermostat, checking and replacing the air filter, confirming the furnace switch and breaker are on, keeping supply registers and return grilles open, and clearing snow, ice, or debris from outdoor vent and intake terminations. Never bypass, jumper, or reset safety switches (limit, flame-rollout, or pressure switches), never open the gas valve or burner compartment, and never attempt combustion, electrical, or control-board repairs yourself. Error codes point toward a problem but are not a substitute for proper diagnosis — when in doubt, turn the system off and call a licensed HVAC technician. Keep working carbon-monoxide detectors on every level of your home.
When to call a pro: A repeatedly tripping limit, and any rollout-switch trip, must be inspected by a licensed technician — never reset or bypass a rollout switch. If you smell gas or see soot, shut the furnace off, leave, and call your gas utility or 911 from outside.
American Standard furnace 5 flashes FAQ
What does American Standard furnace 5 flashes mean?
Open limit or rollout switch — a high-temperature limit or flame-rollout safety switch has opened, indicating overheating or flame rollout.
What causes American Standard furnace 5 flashes?
Common causes: Low airflow from a dirty filter, blocked returns, or a dirty blower wheel; Blocked or restricted flue causing overheating; Over-firing / outlet gas pressure set too high (pro adjustment); Failed limit or rollout switch.
Can I fix American Standard furnace 5 flashes myself?
You can safely try: Replace or clean the air filter immediately — restricted airflow is the most common cause; Make sure all supply and return vents are fully open and unobstructed; Let the furnace cool, then power-cycle once at the breaker. A repeatedly tripping limit, and any rollout-switch trip, must be inspected by a licensed technician — never reset or bypass a rollout switch. If you smell gas or see soot, shut the furnace off, leave, and call your gas utility or 911 from outside.
Sources: manualslib.com. General information for homeowners, not professional advice — confirm against your furnace's manual and a licensed technician.