February 9, 2024
Frequently Encountered Furnace Issues & Remedies

Nothing’s worse than shivering inside your own home when the furnace acting strange. From funny smells to loud noises, any funky furnace behavior can be cause for concern.

Sure, professionals can help. But before you call, try some DIY troubleshooting below. A few easy fixes might get your heat humming again.

Read on!

The Furnace Won’t Start

You jack up the thermostat, but the furnace refuses to start. Try these tips to get the heat flowing:

  • Double check the thermostat setting. Duh, but make sure it’s actually high enough to trigger the furnace.
  • Verify the power is on. Check breakers and reset any tripped ones in your electrical panel.
  • Confirm the furnace power switch is flipped to “on.” There’s usually a separate switch on or near the unit itself.
  • Let an overheated motor reset. If the motor overloaded, wait 30 minutes before pushing the reset button by the motor housing. Still dead? Wait another 30 and try again. If no luck after the third time, call a pro.
  • Relight the pilot if it went out. Clean the pilot opening, hold the pilot button down fully, and confirm the gas valve is open.
  • Make sure fuel is flowing. Verify the gas valve is completely open and supplying the furnace.

The Furnace Doesn’t Produce Enough Heat

The furnace runs, but your home never warms up to the set temperature. Some common causes:

  • Dirty filter. Swap in a fresh filter according to manufacturer guidelines. Debris buildup restricts airflow.
  • Clogged blower. Carefully clean out the blower assembly so air flows freely again.
  • Blocked registers. Check for closed vents and clear any obstructions from furniture, rugs, drapes, etc.
  • Loose blower belt. Tighten or replace a loose belt – you may need a pro’s help for this one.
  • Dirty burners. Burners need periodic cleaning to work efficiently. Call a technician.
  • Imbalanced system. Rebalancing air flow requires an HVAC pro.

The Furnace’s Burner Won’t Stay Lit

If your furnace ignites then shuts down repeatedly, the burner flames are going out too soon. This halts operation until the ignition sequence starts again. Here are some common culprits behind an uncooperative burner:

  • Loose or faulty thermocouple – Tighten the thermocouple nut slightly or replace if damaged. This part tells the furnace a flame is present.
  • Dirty flame sensor – Gently clean with steel wool or replace the sensor. It detects the burner flame.
  • Weak pilot light – Adjust the pilot flame to around 2 inches high for proper ignition.
  • Malfunctioning electric pilot – Only a professional can fix this issue.
  • Tripping pressure switch – Improper venting can cause this. Check for clogged filters, blocked vents, or duct obstructions restricting airflow.

The Blower Runs Constantly

In normal operation, your furnace should heat the house then cycle off until temperature drops again.

But if the blower runs non-stop regardless of whether the burner ignites, here’s what may need fixing:

  • Incorrect thermostat setting – Make sure the fan control is set to “auto” not “on.”
  • Stuck limit switch – Try resetting this safety component. If that doesn’t work, a pro will need to replace it.
  • HVAC system imbalance – Rebalancing air flow requires a technician’s expertise.

The Furnace Operates Loudly

Loud furnace noises usually mean some component is loose or wearing out. Don’t ignore them – have an HVAC technician inspect and repair the cause. Here are some of the most common noisy furnace sounds and likely fixes:

  • Rhythmic knocking – Indicates struggling ignition system. A pro can adjust gas flow.
  • Hum that increases over time – Worn out blower motor needs replacement.
  • Clanking or banging – Secure any loose internal parts making contact.
  • High-pitched whistle – Signals airflow restriction. Change filters, open vents, clean blower.
  • Snapping at startup – Repair needed on ignition system.
  • Cracking during operation – Debris in burners obstructing flames. Professional cleaning recommended.

Finally, remember that unexpected loud noises can signify potentially dangerous situations like a gas leak. Always err on the side of caution and request professional service for any concerning new furnace sounds.

Weird Smells

Unusual odors indicate a problem. Be careful, as some can signal dangerous gas leaks.

  • Burning smell – Replace the filter if it’s clogged with debris. Otherwise, a pro should check for motor or electrical issues.
  • Gas smell – This could mean a serious leak! Open windows and shut off gas to the unit. Call the gas company immediately. Don’t turn furnace back on until the leak is fixed.
  • Oily smell – Have an HVAC technician clean and tune-up the motor. It could be overheating due to lack of maintenance.
  • Rotten eggs/sulfur – Some odor from condensation is normal at start-up, but a strong constant smell indicates a cracked heat exchanger. Shut down the furnace and contact a pro to replace the heat exchanger before using it again.

Water Leaks from the Furnace

These units condense moisture from the air as part of their operation. But too much liquid indicates an issue.

If you notice an overflowing leak near your furnace, here’s how to troubleshoot:

  • Check the condensate hose for clogs – Blow out any gunk blocking the plastic drain line. Kinks can prevent water from draining properly.
  • Inspect the condensate pan – Make sure the pan under the furnace isn’t overfilling with water. If it’s not draining right, the safety float switch may need cleaning so it can open the drain valve.

If you can’t find the source of the leak, play it safe and call in an HVAC technician. A pro can pinpoint any problems with the condensate drainage system. Ignoring a furnace leak could lead to water damage or mold down the line.

Schedule Preventative Furnace Maintenance

Like any complex machine, furnaces require regular upkeep and tune-ups to avoid untimely breakdowns. Preventative maintenance allows technicians to spot minor issues before they become major repair headaches. Don’t wait until you have no heat – invest in annual furnace inspections to keep your system running reliably all winter long.

Of course if your furnace already stopped working, prompt service is key to getting back to cozy temperatures. Whether you need maintenance or emergency repairs, the experts at Indoor Comfort Heating & Air Conditioning can help. Contact us at at 505-933-2700 to schedule reliable furnace service and finally say goodbye to shivering inside your own home!

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