Gone Cold: 5 Common Furnace Issues, and How to Fix Them

The furnace is one of the essentials of the modern home, especially if you live in a cold weather region. A properly functioning furnace is necessary to stay warm and comfortable, as well for maintaining proper indoor temperature for your furniture and appliances. 

But like any other home appliance, furnaces can experience various issues that could disrupt their performance. In this guide, we tackle the different types of problems commonly seen in furnaces and provide practical solutions for each. 

Whether you’re a homeowner or a DIY enthusiast, understanding these issues and their fixes can help you save money on repairs and ensure your furnace operates efficiently.

Common Furnace Problem #1: Lack of Heat 

Low or inadequate heating is the most common complaint we receive at Total Home Supply. These can be caused by three main factors:

☒ Thermostat Malfunction

Issue: 

If the thermostat is not functioning correctly, it may not signal the furnace to produce heat.

Solution:

Check and calibrate the thermostat. Replace batteries if needed. If problems persist, consider replacing the thermostat.

☒ Dirty or Faulty Ignitor

Issue: 

A dirty or malfunctioning ignitor can prevent the furnace from igniting and producing heat.

Solution: 

Clean the ignitor using a soft brush. If the problem persists, replace the ignitor as it may be damaged.

☒ Gas Supply Issues

Issue: 

Insufficient or interrupted gas supply can lead to a lack of heat.

Solution: 

Ensure the gas valve is open and the supply line is unobstructed. If problems persist, consult a professional to check for gas leaks or supply issues.

☒ Blown Fuse

Issue:

If the thermostat is set to “Heat” and working, the circuit breaker may have tripped.

Solution:

Check the home’s breaker panel. Look for the furnace circuit to see if it’s thrown to the Off position. Test the breaker by flipping it back and forth. Reset by leaving it to the On position.

☒ Loose Access Panel

Issue:

Some furnace doors are equipped with a safety switch. If the door is improperly latched, the safety switch stops the fan and burner from activating.

Solution:

Check that the access panel is securely closed and restart the furnace.

Common Furnace Problem #2: Low Airflow

Furnaces are forced air systems. That is, they work by distributing heated air throughout the home. When the airflow is low or interrupted, it impacts the distribution of heat.

☒ Clogged Air Filter

Issue:

A dirty or clogged air filter restricts airflow, reducing the furnace’s efficiency.

Solution:

Regularly replace or clean the air filter, typically every 1-3 months. This simple maintenance task can significantly improve airflow and system efficiency.

☒ Blocked Vents or Ducts

Issue: 

Obstructed vents or ducts hinder proper airflow, leading to uneven heating or a complete system shutdown.

Solution:

Inspect vents and ducts for blockages or debris. Furniture, appliances, or household objects may also be blocking the vents. Remove any obstacles and ensure proper ventilation throughout the entire system.

☒ Blower Maintenance

Issue:

The low airflow may be caused by an unmaintained blower. The blower is the part that draws the heat from the furnace and distributes it through the ductwork.

Solution:

Make sure the blower is properly lubricated. The blower motor should be oiled at least once a year.

Common Furnace Problem #3: Strange Noises

A noise emanating from the furnace can be a cause for concern, depending on the type of noise generated.

☒ Loud Banging or Popping

Issue: 

The expansion and contraction of ducts or heat exchangers can cause loud noises. While minor, they can be annoying, especially if they occur frequently or at night.

Solution: 

Hire a professional to inspect and secure loose ducts or components. Regular maintenance can prevent these issues.This is also sometimes caused by improper venting.

☒ Squealing or Whining Sounds

Issue: 

This could indicate loose or faulty parts. Loose or damaged belts, bearings, or fan blades can produce high-pitched noises.

Solution:

Tighten or replace loose belts, lubricate bearings, or replace damaged fan blades to eliminate the source of the noise. If the noise persists, then a component may need to be replaced.

Common Furnace Problem #4: Continuous Running

A furnace that runs nonstop can waste energy and balloon your utility costs. 

☒ Thermostat Issues

Issue: 

Incorrect thermostat settings or a malfunctioning thermostat can cause the furnace to run continuously.

Solution:

Check and adjust thermostat settings. If problems persist, consider replacing the thermostat.

☒ Airflow Restriction

Issue: 

Restricted airflow due to dirty filters or blocked vents can cause the furnace to run longer than necessary.

Solution:

Clean or replace air filters and remove any obstructions in vents to ensure proper airflow.

☒ Limit Switch

Issue:

The blower has a limit switch, which if faulty could cause it to run continuously. This eats up energy while severely shortening the life of the blower.

Solution:

Check if the limit switch is closed. A tripped switch goes into the open position.

Common Furnace Problem #5: Pilot Light or Ignition Problems

☒ Pilot Light Won’t Stay Lit

Issue: 

Thermocouple issues or a dirty pilot assembly may cause the pilot light to go out frequently.

Solution:

Clean the pilot assembly and ensure the thermocouple is positioned correctly. If problems persist, consider replacing the thermocouple.

☒ Ignition Failure

Issue: 

Malfunctioning ignition systems can prevent the furnace from starting.

Solution:

Clean or repair the ignition system components. If needed, replace the ignitor or pilot assembly.

Regular maintenance and prompt attention to furnace issues are crucial for keeping your home warm and comfortable. By understanding the common problems and their solutions, you can troubleshoot minor issues on their own, and only schedule professional assistance when needed. 

At TotalHomeSupply.com, we offer a wide range of furnace parts and accessories to help you address these issues effectively, ensuring your heating system operates efficiently.  

Also check out our guide to Furnace Safety to ensure safe and proper operation of your home furnace!