
8 Common Furnace Problems
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Call Now (442) 222-90048 Common Furnace Problems and What You Can Do About Them

A properly functioning furnace is essential to keeping your home warm and comfortable, especially when the temperature drops. Unfortunately, several issues can cause your heating system to work inefficiently—or stop working altogether. Below are eight common furnace problems homeowners encounter, along with practical steps you can take before calling a professional like Personal Plumbing, Heating & Cooling. While these solutions may help in some cases, remember that HVAC systems can be complex and often require expert hands for a lasting fix.
Call Now (442) 222-90041. Dirty or Clogged Air Filters
What’s the problem?
Over time, furnace filters become clogged with dust, pet hair, and other debris. This restricts airflow, causing the furnace to work harder and potentially overheat.
What you can do:
- Check the air filter monthly and replace it at least every three months (or more frequently if you have pets or allergies)
- Choose a filter with the right MERV rating for your furnace. Too high a rating can actually restrict airflow further if your system isn’t designed for it
Why professional help may be needed:
If your furnace is still struggling after you’ve changed the filter, it might indicate a more serious airflow issue or a malfunctioning blower motor.
2. Thermostat Issues
What’s the problem?
Sometimes, a simple thermostat glitch is the reason your furnace doesn’t turn on or maintain the right temperature. Dead batteries, incorrect settings, or miscalibration can all lead to heating troubles.
What you can do:
- Verify your thermostat is set to “HEAT” and the temperature is higher than room temperature.
- Replace the batteries if they’re running low.
- Check that the thermostat is located away from drafty windows or heat sources that may cause false readings.
Why professional help may be needed:
If your furnace continues to run inconsistently, an HVAC technician can determine whether the wiring or the thermostat unit itself is at fault.
3. Pilot Light or Ignition Concerns
What’s the problem?
For gas furnaces, a faulty pilot light or electronic ignition can keep your furnace from producing heat. Common culprits include a blown-out pilot flame, a dirty igniter, or a malfunctioning thermocouple.
What you can do:
- If you have a traditional pilot light, follow the manufacturer’s instructions to carefully relight it.
- Make sure the gas valve is switched on.
- Gently clean around the pilot assembly if it’s visibly dirty.
Why professional help may be needed:
Gas and electrical components should be handled by a certified professional to avoid safety risks. If your furnace still won’t light, contact an HVAC specialist.
4. Malfunctioning Blower Components
What’s the problem?
The blower motor is responsible for circulating warm air throughout your home. If the motor, belt, or bearings are worn, you might notice weak airflow or unusual squealing sounds.
What you can do:
- Listen for grinding, screeching, or rattling noises. These can indicate worn belts or bearings.
- Check to see if anything is obstructing the blower assembly (but do so with the power switched OFF).
Why professional help may be needed:
Replacing or repairing blower components often requires specialized tools and expertise to avoid damaging the motor or misaligning belts.
5. Furnace Short Cycling
What’s the problem?
Short cycling refers to the furnace turning on and off too frequently without completing a full heating cycle. This can happen due to restricted airflow (e.g., clogged filters) or if the furnace is too large for the home.
What you can do:
- Ensure the air filter is clean and vents are open and unobstructed.
- Verify thermostat placement; if it’s near a heat source, it may cause the furnace to cycle off prematurely.
Why professional help may be needed:
If changing filters and adjusting the thermostat doesn’t solve the problem, you may need an HVAC inspection to diagnose deeper mechanical or sizing issues.
6. Furnace Making Strange Noises
What’s the problem?
Banging, clanking, squealing, and rumbling can all signal something amiss inside your furnace. Loose parts or mechanical breakdowns are common reasons for these noises.
What you can do:
- Pinpoint where the noise is coming from if possible (e.g., the blower area, near the burner, or the ductwork).
- Tighten any easily accessible screws or panels (with the power OFF, for safety).
Why professional help may be needed:
A professional technician can safely identify and correct the exact source of unusual sounds—whether it’s a failing motor, misaligned belt, or other mechanical defect.
7. High Energy Bills
What’s the problem?
A sudden spike in your heating bill often indicates your furnace is running inefficiently, either because it’s working overtime or losing heat due to a malfunction.
What you can do:
- Check for leaking ductwork or blocked vents.
- Inspect and replace filters to ensure smooth airflow.
- Review your thermostat settings—sometimes a small adjustment can lower bills significantly.
Why professional help may be needed:
An HVAC specialist can assess your system’s overall efficiency and recommend upgrades or repairs that will help reduce energy costs long-term.
8. Lack of Maintenance
What’s the problem?
Regular tune-ups are crucial for catching minor issues before they escalate. Dust buildup, worn parts, or small cracks in heat exchangers often go unnoticed without routine inspections.
What you can do:
- Schedule annual furnace inspections, ideally before the heating season starts.
- Keep the area around your furnace clear to allow easy access for cleaning and repairs.
- Replace filters regularly and keep track of any performance changes throughout the year.
Why professional help may be needed:
A professional maintenance check can reveal hidden problems like cracked heat exchangers (which can leak carbon monoxide) and recommend proactive fixes to avoid breakdowns in the middle of winter.
Ready for Professional Assistance?
Whether it’s a simple fix like changing out a clogged filter or something more complex like a failing blower motor, it’s always best to get an expert opinion if your furnace isn’t running at its best. If you live in Mission Viejo or the surrounding areas, Personal Plumbing, Heating & Cooling has you covered. Our experienced team is dedicated to identifying the root cause of your furnace problems and delivering prompt, reliable repairs.
Contact Personal Plumbing, Heating & Cooling today for fast, friendly furnace service—you’ll gain peace of mind knowing your home is in good hands, and you’ll enjoy a warm and comfortable environment all season long. Let us help you stay cozy and worry-free!
Call Now (442) 222-9004