February 14, 2025

[Video] Why Isn’t My Furnace Working?

When the temperature drops in Denver, the last thing you want is to discover your furnace is not working. In this unfortunate situation, there are several things you can check to diagnose and remedy the problem. The video below shows how to troubleshoot the most common furnace issues. In the rest of this blog, we look at the more significant issues an HVAC technician can address if the problem persists.

DIY Furnace Troubleshooting: What You Should Check

Before calling a professional furnace repair company, here are several steps you can take to diagnose and potentially fix the issue:

1. Check the Thermostat

Your thermostat turns your furnace off and on and controls the temperature. If it is not working properly, your furnace may not function either.

• Ensure the thermostat is set to “heat” mode.
• Check that the temperature setting is higher than the current room temperature.
• If your thermostat is battery-operated, replace the batteries.
• Consider resetting the thermostat to see if that restores functionality.

2. Inspect the Circuit Breaker

A tripped circuit breaker could prevent your furnace from getting power. 

• Locate your electrical panel and check if the furnace breaker has tripped.
• If it has, reset it by turning it off and back on.
• A breaker that continues to trip may be an electrical issue requiring a professional HVAC technician.

3. Check the Furnace Filter

A clogged or dirty air filter can restrict airflow and cause your furnace to shut down.

• Locate the filter, remove it, and check for dust buildup.
• If the filter is dirty, replace it with a new one to ensure proper airflow.

4. Examine the Pilot Light or Ignition System

Gas furnaces installed before 2010 will have a visible pilot light that ignites the burner when your furnace turns on. 

• If your furnace has a standing pilot light, ensure it is lit. If not, follow the manufacturer’s instructions to relight it.
• For newer furnaces with an electronic ignition, listen for clicking sounds when the furnace tries to start. This may indicate an ignition issue that requires professional repair.

5. Ensure Vents and Registers Are Clear

Blocked vents can restrict airflow and cause the furnace to overheat and shut down.

• Ensure all supply and return vents in your home are open and unblocked.
• Have your vents and ducts cleaned annually. 

6. Check for Error Codes

Many modern furnaces have a diagnostic LED light that flashes error codes.

• You may need to remove the front panel of your furnace to see the lights.
• Refer to your owner’s manual to decode the blinking light pattern, which may indicate a specific problem.
• If you are unable to address the issue yourself, call a professional.

6 Common Furnace Problems a Technician Will Check

A licensed HVAC technician can conduct a more in-depth inspection to determine why your furnace isn’t working. Here’s what they typically check:

1. Blower Motor and Fan

The blower fan circulates warm air through your home. If it isn’t working, your furnace won’t distribute heat effectively, and your home will feel cold. 

• A technician will test the motor, lubricate moving parts, and check for blockages.
• They will replace the fan motor if your furnace blower isn’t working.

2. Ignitor and Flame Sensor

The ignitor starts the heating process, while the flame sensor ensures the gas burns correctly. If either of these components is faulty, the furnace may fail to ignite or will shut off prematurely.

• Your furnace technician will check, clean, or replace these parts as needed.

3. Thermocouple and Gas Valve

For furnaces with a standing pilot light, the thermocouple is a safety device that shuts off the gas supply if the pilot light goes out.

• A faulty thermocouple or gas valve can be replaced to restore your furnace to safe operation. 

4. Heat Exchanger Inspection

The heat exchanger transfers heat from the furnace to the air in your home. Cracks in this component can lead to dangerous carbon monoxide leaks.

• A technician will inspect it for signs of damage and recommend repairs or replacement if needed.

5. Electrical Components and Wiring

Loose or damaged wiring can lead to furnace failures or safety hazards.

• Technicians test and secure connections to prevent future breakdowns.

6. Testing the System’s Safety Features

Each model will have its own set of features and precautions. 

• Your HVAC professional will check the high-limit switch, pressure switch, and other safety mechanisms to ensure your system operates safely.

The Value of Hiring a Professional HVAC Technician

While some furnace issues can be resolved with simple troubleshooting, many problems require professional expertise. Here’s why hiring a licensed furnace repair expert is beneficial:

• Safety: Gas and electrical components can be dangerous if you’re not trained to work with them. 
• Proper Diagnosis: A professional can accurately identify the root cause of furnace malfunctions.
• Efficiency: Technicians have the tools and experience to fix issues on the spot so that your heat is restored quickly. 
• Preventative Maintenance: Regular professional inspections can extend the lifespan of your furnace and prevent costly breakdowns.

Contact Applewood for Furnace Repairs Today!

If your furnace isn’t working and you need expert diagnostic and repair services, Applewood is here to help. Call 303-328-3060 or schedule your service online. Our prompt and responsive team is dedicated to getting your heat working quickly.