What's actually causing this
Furnaces fail to heat when the filter is clogged (causing overheating and shutdown), the pilot light or ignitor has failed, the thermostat is misconfigured, or the system enters a safety lockout due to a repeated ignition failure.
What you'll need
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Step-by-step fix
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1
Check the thermostat
Set it to HEAT, set the temperature 5 degrees above room temperature, and confirm the fan is set to AUTO. Replace batteries if the display is dim.
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2
Check the filter
A clogged filter causes the furnace to overheat and shut down on a safety limit. Replace the filter if it's gray and dense.
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3
Check the circuit breaker
Find the furnace breaker in the panel. Reset it if tripped. Also check the furnace power switch (looks like a light switch near the unit).
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4
Read the diagnostic LED
Open the furnace access panel and find the small LED on the control board. Count the blinks — most furnaces include a blink code chart on the inside of the panel door.
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5
Check the condensate drain (high-efficiency furnaces)
High-efficiency furnaces produce condensation. If the drain is clogged, the furnace shuts down. Find the PVC drain line and clear it with a wet/dry vac.
HVAC technicians in Minneapolis typically charge $115–185/hr. Annual maintenance runs $150–300, while furnace or A/C replacement costs $4,000–8,000+.
Minnesota requires EPA certification and licensing. Permits required.
Heating is absolutely critical. Boiler and furnace systems are essential. Central air is becoming more standard but heating is dominant. Extreme cold means insulation and weatherization are critical. HVAC maintenance during winter is essential.
Minneapolis has moderate humidity levels. HVAC systems handle both heating and cooling loads through the year. Regular filter changes and annual maintenance are important for efficiency. Winter heating demand is significant. Furnace failure during cold snaps can be a safety emergency — schedule maintenance before the heating season begins.
DIY in Minneapolis: Minneapolis's moderate licensing and cold-climate focus support some DIY work. Winterization, freeze prevention, and water softener maintenance are common homeowner tasks. Extreme freeze risk makes professional HVAC and plumbing maintenance critical.
- The furnace ignites but shuts off within 30 seconds — flame sensor issue requiring a tech.
- You smell gas — leave the house and call the gas company.
- The furnace is making loud banging or scraping sounds.
- The blink code indicates a pressure switch or inducer motor fault.
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