🔥 Troubleshooting Tips — What to Do If Your Furnace Isn’t Heating Properly
🔧 Why Furnaces Stop Heating
Nothing is more frustrating than a furnace that refuses to keep your home warm. Furnaces can fail to heat for numerous reasons — from simple filter issues to complex gas supply or ignition problems. Your Goodman two-stage furnace is built for reliability, but even the best systems need troubleshooting from time to time.
Proper diagnosis can save you money, prevent costly repairs, and ensure your home stays safe and comfortable. In this guide, we’ll cover common furnace problems, step-by-step troubleshooting, preventive maintenance, and when to call a professional.
🌡️ 1. Check Your Thermostat First
Your thermostat acts as the command center of your heating system. Even a perfectly functioning furnace won’t run if the thermostat isn’t sending the correct signals.
Troubleshooting Steps:
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Make sure the thermostat is set to “Heat” and the temperature is higher than the current room temperature.
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Replace old batteries if it’s battery-powered.
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Ensure that the thermostat is level and free from dust, which can interfere with sensor readings.
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For digital models, check for error codes or warning lights. Some modern thermostats can even alert you to communication issues with your furnace.
Tip: Smart thermostats can sometimes lose connection after a power outage. Reboot or reset according to the manufacturer’s guide.
External Link: For more tips on troubleshooting thermostats, see Honeywell’s Thermostat Troubleshooting Guide.
🌬️ 2. Inspect and Replace Air Filters
One of the most common causes of poor furnace performance is a dirty or clogged air filter. Restricted airflow can cause your furnace to overheat, shut down prematurely, or fail to heat certain rooms.
Step-by-Step:
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Locate the air filter, usually behind a vent or panel on the furnace.
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Remove the filter and inspect it for dust, debris, or pet hair.
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Replace it if it looks dirty or clogged.
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Depending on usage, filters should be replaced every 1–3 months.
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Consider upgrading to MERV 8 or higher for better indoor air quality.
Pro Tip: Homes with pets, smokers, or high dust levels may need monthly filter changes.
External Link: Learn more about proper filter maintenance at Energy Star.
🛠️ 3. Check the Circuit Breaker and Power Supply
Sometimes the problem isn’t with the furnace itself — it’s the power supply.
Steps:
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Ensure the furnace’s circuit breaker hasn’t tripped.
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Verify the furnace switch (near the unit, looks like a light switch) is on.
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If a breaker has tripped, reset it.
Tip: Frequent tripping may indicate a deeper electrical issue or furnace overload. Never ignore repeated electrical trips.
External Link: The U.S. Department of Energy provides guidance on safe electrical inspections for HVAC systems.
🔥 4. Examine the Ignition System or Pilot Light
Older furnaces use a pilot light, while modern Goodman models rely on electronic ignition. A failure here will prevent your furnace from heating.
For Pilot Light Furnaces:
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Make sure the pilot light is lit.
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Relight according to the furnace manual if it’s out.
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Inspect the thermocouple, which senses the flame; replace if worn.
For Electronic Ignition Furnaces:
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Check the ignitor for cracks or discoloration.
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A faulty ignitor may require professional replacement.
Safety Note: Never attempt to repair the gas ignition system without proper knowledge. Gas safety is critical.
NFPA Furnace Safety Guidelines explain safe handling of pilot lights and electronic ignitors.
🌬️ 5. Inspect the Gas Supply
A furnace won’t heat if it isn’t receiving a steady supply of natural gas.
Steps:
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Ensure the gas valve is open.
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Verify that other gas appliances are working properly.
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If you smell gas or hear hissing, evacuate your home immediately and call your gas provider.
Important: Never attempt DIY repairs for gas line problems. Always rely on licensed technicians.
External Link: For more guidance, see the U.S. Consumer Product Safety Commission Gas Safety Page.
🛠️ 6. Inspect the Furnace Blower Motor
The blower motor circulates warm air throughout your home. If it malfunctions, it may feel like the furnace isn’t heating, even if the burners are working.
Inspection Tips:
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Listen for unusual noises such as squealing, grinding, or rattling.
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Inspect for dust buildup around the blower.
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Check the blower belt for cracks or looseness.
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Lubricate bearings if applicable.
A malfunctioning blower may require professional repair or replacement.
AHRI Resources provide detailed guidance on blower motor inspection and maintenance.
🔥 7. Check the Flame Sensor
The flame sensor ensures safe operation by detecting whether the burners are igniting. A dirty sensor can cause the furnace to shut off unexpectedly.
Steps:
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Locate the flame sensor near the burners.
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Remove it and gently clean it with fine steel wool or a soft cloth.
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Reinstall and test the furnace.
🌬️ 8. Look for Blocked Vents or Ductwork
Restricted airflow can prevent warm air from reaching your rooms and cause overheating.
Steps:
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Ensure vents are fully open and unobstructed by furniture or drapes.
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Check for debris in return air ducts.
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Inspect ductwork for leaks or disconnected joints.
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Seal leaks with mastic or HVAC-rated duct tape.
EPA Duct Sealing Guidelines explain proper duct inspection and sealing.
🔧 9. Test Limit Switches and Safety Controls
Furnaces have limit switches to prevent overheating and pressure switches to ensure airflow.
What to Do:
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Reset any tripped limit switches.
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Inspect pressure switches for proper function.
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Replace faulty components promptly.
ASHRAE Safety Standards provide in-depth info on furnace safety controls.
🔥 10. Inspect the Heat Exchanger
A cracked heat exchanger is a major safety concern and can cause carbon monoxide leaks.
Signs of Damage:
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Furnace blowing cold air intermittently
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Strange noises during operation
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Rust or corrosion inside the furnace
Important: Never attempt to repair a heat exchanger yourself. Always call a licensed HVAC technician.
Visit CPSC HVAC Safety for more safety guidance.
🛠️ 11. Check the Furnace Control Board
Modern Goodman furnaces have a digital control board with LED indicators that show error codes.
Steps:
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Observe the control board for blinking lights or error codes.
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Refer to your furnace manual for code interpretation.
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Reset the system if necessary, or call a technician for persistent errors.
Goodman Manufacturing Troubleshooting Guide provides a list of common codes and solutions.
🌬️ 12. Inspect for Strange Noises
Noises often indicate mechanical or operational issues.
Listen for:
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Banging or popping — delayed ignition.
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Squealing or grinding — blower motor or belt issues.
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Rattling — loose panels or debris.
Addressing issues early prevents major repairs.
🔥 13. Seasonal and Climate Considerations
During winter, furnaces work harder. Common issues include:
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Frost on pipes (hybrid systems)
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Delayed ignition due to cold gas lines
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Airflow restriction from frozen vents
Tip: Keep the furnace and surrounding area clear of ice, snow, and debris.
Department of Energy Winter Furnace Tips offers seasonal maintenance guidance.
🛠️ 14. When to Call a Professional
DIY troubleshooting is helpful, but some issues require professional intervention:
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Gas supply problems
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Cracked heat exchangers
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Persistent ignition or blower failures
A licensed HVAC technician ensures your furnace operates safely, efficiently, and in compliance with local codes.
🌟 15. Preventive Maintenance for Long-Term Reliability
Preventive maintenance reduces the likelihood of furnace failures:
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Annual tune-ups by a professional
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Seasonal filter changes
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Cleaning of the blower and burners
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Inspecting venting and ductwork
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Testing safety controls and thermostats
Regular upkeep prolongs the lifespan of your furnace and ensures consistent home comfort.
💡 Final Thoughts
A furnace that isn’t heating properly can be stressful, but with the right knowledge, you can diagnose, troubleshoot, and prevent many common issues. From checking your thermostat and filters to inspecting the ignition system, blower, and ductwork, homeowners have a lot of power to keep their Goodman two-stage furnace running efficiently.
When in doubt, don’t hesitate to call a professional — safety comes first, especially when dealing with gas-powered heating systems.
In the next blog we shall learn more about Gas Furnace vs. Heat Pump — Which Heating System Wins for Your Climate?
