When your furnace stops behaving the way it should — blowing cold air, cycling too often, or refusing to start altogether — panic can set in fast. But before you imagine freezing nights and costly repairs, take a deep breath.
Savvy knows that many furnace issues are easy to diagnose and fix, especially with Goodman’s built-in diagnostic features and a little homeowner know-how.
This comprehensive guide walks you through the most common furnace problems, what causes them, and exactly what to do — safely and confidently — before you call in the pros.
🔍 Why Troubleshooting Matters
A modern furnace like the Goodman GRVT961005CN is engineered for efficiency, but even the best system can run into small issues caused by dust, airflow restrictions, or sensor buildup.
The good news? Most of these problems are simple and preventable.
According to Energy.gov, over 80% of furnace failures are linked to airflow blockages or neglected maintenance — issues homeowners can often handle themselves.
When you troubleshoot early, you:
✅ Prevent small problems from becoming costly breakdowns
✅ Maintain energy efficiency and even heating
✅ Extend your furnace’s lifespan
✅ Avoid unnecessary service calls
Savvy says: “A smart homeowner doesn’t wait for a breakdown — they listen, look, and act early.”
⚡ Safety First — Before You Start
Before you do any troubleshooting, protect yourself and your home.
Here are Savvy’s golden safety rules:
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Shut off the furnace’s power at the breaker panel.
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Turn off the gas supply if you smell gas or suspect a leak.
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Don’t open sealed combustion components — leave those for certified technicians.
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Wait until the unit cools before handling panels or internal parts.
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Keep a carbon monoxide detector near your furnace for peace of mind.
For more safety guidance, check the Consumer Product Safety Commission’s Gas Appliance Safety Guide.
🧊 Issue #1: Furnace Won’t Turn On
It’s a classic winter panic moment — you turn up the thermostat, but your furnace won’t start.
❄️ Possible Causes:
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Tripped circuit breaker or power switch off
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Loose wiring or safety switch triggered
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Thermostat malfunction or misconfiguration
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Faulty flame sensor or ignitor
✅ Savvy’s Fixes:
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Check the breaker box. Look for a tripped switch labeled “Furnace” and reset it if necessary.
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Inspect the furnace power switch. It looks like a regular light switch near the unit — make sure it’s turned on.
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Ensure the thermostat is set to “Heat.” Increase the temperature a few degrees higher than the current room reading.
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Check the furnace door. Goodman units have a door safety switch — the unit won’t run if the panel isn’t fully closed.
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Listen for clicking sounds. If the system hums but doesn’t ignite, you may have a dirty flame sensor.
If you’ve checked these and the furnace still won’t start, it’s time to call a professional to inspect ignition components or gas flow.
🌬️ Issue #2: Weak or No Airflow
If your furnace is running but barely pushing air through the vents, the problem is almost always linked to airflow restrictions.
🌪️ Possible Causes:
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Clogged or old air filters
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Blocked supply or return vents
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Dirty blower wheel or motor
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Collapsed or disconnected duct
✅ Savvy’s Fixes:
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Replace your filter. If it’s gray, dusty, or older than 3 months, swap it out immediately.
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Check all vents. Make sure furniture or rugs aren’t blocking airflow.
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Clean vent grilles and registers. Use a vacuum brush attachment to remove dust buildup.
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Inspect ducts for leaks or disconnections. Look for gaps in visible sections, especially near the furnace.
The ENERGY STAR filter maintenance guide notes that replacing a dirty filter can lower energy use by up to 15%.
Savvy Tip: “If your system is running but airflow feels weak, your furnace is probably fine — it just can’t breathe.”
🔥 Issue #3: Furnace Turns On but Doesn’t Heat
Few things are more confusing than a furnace that blows air but doesn’t get warm.
🔎 Possible Causes:
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Ignitor or pilot light failure
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Dirty flame sensor
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Faulty gas valve
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Blocked intake or exhaust vents
✅ Savvy’s Fixes:
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Check your thermostat batteries. Low battery power can cause false readings.
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Inspect the flame color. A healthy flame burns steady blue; yellow or orange indicates incomplete combustion.
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Clean the flame sensor. Turn off the furnace, remove the sensor, and gently polish it with fine steel wool.
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Clear exterior vents. Ensure your intake and exhaust pipes aren’t blocked by snow, leaves, or debris.
If ignition doesn’t occur after multiple cycles, contact a licensed HVAC tech — repeated resets can flood your furnace with unburned gas.
Learn more from ACHR News – Troubleshooting Gas Furnace Ignition Systems.
🌀 Issue #4: Furnace Short Cycles (Turns On and Off Too Often)
When your furnace keeps cycling every few minutes, it’s working harder than it should — and wasting fuel.
🔄 Possible Causes:
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Dirty air filter (yes, again)
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Thermostat near a heat source
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Blocked flue or exhaust vent
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Oversized furnace for your home
✅ Savvy’s Fixes:
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Replace your filter. Most short-cycling starts here.
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Relocate the thermostat. If it’s near a kitchen, lamp, or sunlight, it may shut the furnace off prematurely.
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Inspect the vent pipe. A blockage can trigger safety sensors and shut down heating cycles.
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Call a technician. If cycling continues, your furnace may be too powerful for your home size.
According to Energy.gov, short cycling reduces efficiency by up to 30% and increases wear on blower motors.
Savvy says: “If your furnace acts like it’s out of breath, it’s not lazy — it’s struggling to find balance.”
💨 Issue #5: Loud or Unusual Noises
Furnaces shouldn’t sound like a drum solo. Clicking, banging, or rattling noises mean something’s loose, dirty, or starting to wear out.
🎧 Common Sounds & What They Mean:
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Boom or Bang: Delayed ignition due to dirty burners.
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Squealing: Worn blower bearings or loose belts.
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Rattling: Loose panels or vent screws.
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Grinding: Motor failure — shut it down immediately.
✅ Savvy’s Fixes:
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Tighten screws and panels.
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Clean the blower fan. Dust on blades causes imbalance.
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Lubricate bearings (if applicable). Older models may require occasional oiling.
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Call a professional if the sound is metallic, grinding, or explosive.
Savvy Tip: “A little rattle can become a big repair. When your furnace starts talking, it’s time to listen.”
💧 Issue #6: Water Pooling Around Furnace
Finding water near your furnace can be alarming, but it’s often an easy fix — especially in high-efficiency condensing models like Goodman’s.
💧 Possible Causes:
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Clogged condensate drain line
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Loose drain hose connections
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Cracked collector box
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Improper vent slope
✅ Savvy’s Fixes:
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Shut off power to the furnace.
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Check the condensate drain line. If it’s clogged, flush it with a 3:1 water-vinegar solution.
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Tighten hose fittings on both ends.
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Ensure vent pipes slope slightly downward toward the furnace drain.
Reference: Family Handyman – How to Clean Condensate Lines.
If water returns after cleaning, a cracked collector box or internal leak may require professional service.
🌡️ Issue #7: Uneven Room Temperatures
Cold bedrooms and overheated living rooms are more than comfort issues — they signal airflow imbalance.
🌬️ Possible Causes:
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Duct leaks or undersized registers
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Blocked vents or furniture placement
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Thermostat miscalibration
✅ Savvy’s Fixes:
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Open all vents. Closed vents create pressure imbalances.
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Seal visible duct leaks with foil tape or mastic sealant.
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Check thermostat accuracy. Compare with a portable room thermometer — recalibrate if readings differ by more than 2°F.
ENERGY STAR’s duct sealing guide shows how small leaks can waste 20–30% of conditioned air.
Savvy Tip: “Your furnace can only do its job if your ducts do theirs.”
🧠 When to Call a Professional
Sometimes the safest and smartest fix is knowing when to stop.
🚨 Call a Licensed Technician If:
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You smell gas or burning odors.
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Your furnace repeatedly shuts off after startup.
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You see standing water inside the cabinet.
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Your carbon monoxide alarm activates.
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The control board flashes continuous error codes.
Choose certified contractors through the Air Conditioning Contractors of America (ACCA) or NATE. Professionals can perform full diagnostics and maintain your warranty coverage.
Savvy says: “DIY stops where danger begins. When gas, wiring, or flame sensors are involved — let the pros handle it.”
🛠️ Goodman’s Built-In Diagnostic Tools
Goodman makes troubleshooting easier than ever with smart, built-in features designed for homeowners and technicians alike.
🧩 Key Diagnostic Features:
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LED Error Codes: The control board flashes sequences that pinpoint the exact issue — from dirty filters to pressure switch faults.
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Self-Resetting ECM Blower Motor: If an airflow fault is detected, the system safely resets without damaging the motor.
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ComfortBridge™ Smart Communication: Adjusts heating stages automatically and reports performance data to compatible smart thermostats.
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Integrated Safety Sensors: Shut down the system automatically if overheating or vent blockage occurs.
You can cross-reference error codes in your Goodman user manual or the Goodman Furnace Diagnostic Guide.
Savvy Tip: “Goodman gives you clues before it gives you problems — all you have to do is read the lights.”
🧩 Preventing Future Problems
The best troubleshooting strategy is prevention.
Savvy keeps her furnace running smoothly with:
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Regular filter changes (every 60 days).
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Seasonal vent and duct inspections.
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Annual professional tune-ups.
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A smart thermostat to monitor runtime efficiency.
The Air Conditioning Contractors of America (ACCA) recommends yearly tune-ups for all gas furnaces to maintain safety, efficiency, and warranty coverage.
🏁 Savvy’s Final Verdict — Stay Calm, Stay Safe, Stay Warm
A furnace issue doesn’t have to mean a disaster. With a little understanding and a steady hand, most problems can be identified — and sometimes even fixed — before they interrupt your comfort.
Here’s what to remember:
✅ Start with airflow — it’s the cause of most issues.
✅ Check your thermostat settings and power supply.
✅ Listen for new sounds — they’re your furnace’s way of asking for help.
✅ When in doubt, shut it down and call a pro.
Savvy says: “A quiet furnace is a happy furnace — and Goodman gives you the tools to keep it that way.”
