How to Diagnose Common Furnace Issues

Share this post:

When the cold winter months hit, a functioning furnace is crucial to keeping your home warm and comfortable. However, like any household appliance, furnaces can develop issues over time. Understanding common furnace problems and how to diagnose them can help you determine whether you can fix the issue yourself or if it’s time to call a professional for furnace repair Aurora. This guide covers the most frequent furnace issues and provides tips on diagnosing them.

1. Furnace Not Producing Heat

One of the most common complaints during winter is a furnace that isn’t producing heat. If your furnace runs but doesn’t warm your home, several factors might be causing the issue.

Possible Causes:

  • Thermostat Problems: Start by checking the thermostat. Ensure it’s set to “heat” and that the temperature is set correctly. Sometimes, the problem is as simple as a dead battery or improper settings.
  • Pilot Light Out: If your furnace has a pilot light, it might have gone out. Relighting it can solve the problem, but if it continues to go out, there may be a bigger issue, such as a faulty thermocouple or gas valve.
  • Clogged Air Filter: A dirty air filter can restrict airflow, causing your furnace to overheat and shut down. Check and replace the air filter if necessary.

Diagnosis: If the thermostat is working correctly and the pilot light is lit, but there’s still no heat, it’s time to check for airflow issues or call a professional for furnace repair in Aurora.

2. Furnace Blowing Cold Air

If your furnace is running but only blowing cold air, there could be several underlying problems. This issue is particularly frustrating, especially in freezing temperatures.

Possible Causes:

  • Thermostat Set to “On”: If your thermostat fan setting is set to “on,” the furnace blower will run continuously, even when it’s not heating the air. Set the fan to “auto” so it only runs during heating cycles.
  • Pilot Light or Ignition Problems: If your furnace uses a pilot light or electronic ignition, the issue could stem from these components. If the pilot light is out or the igniter fails, the furnace won’t heat the air properly.
  • Dirty Flame Sensor: Over time, the flame sensor can become dirty or corroded, causing the furnace to shut off the burners. Cleaning the flame sensor can help resolve this issue.

Diagnosis: If you suspect the problem is related to the thermostat settings or ignition components, check these parts first. If you’re not comfortable troubleshooting these elements, seek professional furnace repair in Aurora.

3. Frequent Cycling On and Off

A furnace that frequently cycles on and off without completing a full heating cycle can indicate a problem with its efficiency or internal components.

Possible Causes:

  • Thermostat Malfunction: A faulty thermostat can cause your furnace to turn on and off irregularly. Ensure it is functioning correctly and properly calibrated.
  • Dirty Air Filter: A clogged air filter can restrict airflow, causing the furnace to overheat and shut off prematurely. Regular filter replacement can prevent this issue.
  • Oversized Furnace: If your furnace is too large for your home, it may heat the space too quickly, causing frequent short cycles.

Diagnosis: Start by replacing the air filter and checking the thermostat. If the problem persists, a professional HVAC technician can help diagnose whether your furnace is the right size for your home.

4. Strange Noises

Unusual noises coming from your furnace can signal underlying mechanical issues. If you hear banging, squealing, or rattling, it’s essential to diagnose the cause as soon as possible.

Possible Causes:

  • Loose Components: Rattling or banging noises could be due to loose components such as the blower motor or heat exchanger.
  • Worn Belt or Bearings: Squealing sounds may indicate a worn-out belt or bearings in the blower motor.
  • Ignition Problems: A loud boom or bang when the furnace starts up can be caused by delayed ignition, which could damage the heat exchanger if left unaddressed.

Diagnosis: Turn off the furnace and inspect for loose parts, worn belts, or ignition issues. Strange noises are often a sign that professional furnace repair in Aurora is needed.

5. Furnace Not Turning On

A furnace that won’t turn on at all can be alarming, especially in the middle of a cold winter night. However, there are some steps you can take before calling a technician.

Possible Causes:

  • Thermostat Issues: Ensure the thermostat is set to “heat” and check if the temperature is set above the current room temperature.
  • Blown Fuse or Tripped Circuit Breaker: Check your home’s electrical panel to ensure that the furnace hasn’t blown a fuse or tripped a breaker.
  • Faulty Ignition System: If the furnace’s ignition system is malfunctioning, the unit won’t turn on. This could be due to a faulty pilot light, igniter, or flame sensor.

Diagnosis: If resetting the thermostat or checking the circuit breaker doesn’t resolve the issue, it’s time to call for professional help.

Diagnosing common furnace issues can help homeowners identify minor problems and know when it’s time to seek professional assistance. From thermostat malfunctions to airflow blockages, many furnace problems have simple solutions. However, when issues persist, calling for furnace repair in Aurora ensures that your home stays warm and safe during the colder months. Regular maintenance and timely repairs can prevent small problems from becoming larger, more expensive issues down the line.

Contact Us

    Scroll to Top