person doing DIY furnace tune up tips

The best time for a furnace tune up is before the heating season begins. It’s easier to schedule an appointment with a professional during the off-season, and you can be sure your furnace will run efficiently when you turn it on for the first time. If the heating season is already underway, don’t worry. You can conduct a DIY furnace tune-up at any time.  

A furnace tune-up consists of cleaning, inspecting, and performing routine maintenance. The purpose is to identify potential issues and maximize efficiency to keep your furnace performing well all winter. You could hire a professional to do a more thorough tune-up, but doing a basic tune-up is simple, saves money, and beats neglecting your furnace. A tune-up only requires a few hours of your time and a few essential tools.

Is a Furnace Tune Up Necessary?

Tune-ups are necessary for optimal performance and the extended lifespan of your furnace. Regular tune-ups reduce the likelihood of significant repairs, gas leaks, and carbon monoxide poisoning risks and increase energy efficiency.

The benefits of increased efficiency are twofold. Your furnace will heat your house more effectively, and you will save money on energy costs. The U.S. Department of Energy contends that regular HVAC maintenance and other energy-saving improvements can save you roughly 30% of your energy bill.

How to Do a Furnace Tune Up Yourself

Yearly professional tune-ups are ideal, but a homeowner can perform many of the same maintenance tasks to keep a furnace operating efficiently and identify potential problems before they turn into significant repairs.

Before working on your furnace, take safety precautions. Turn off the power to the unit at the furnace switch, the breaker panel, or both. Switching off the thermostat is not sufficient. Close the gas valve as an additional precaution. If you are nervous about performing any of the tasks below, disregard them. Perform only the tasks with which you are comfortable.

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1. Change Your Furnace Filter

Furnace filters must be changed regularly. Dirty filters impede airflow, force the system to work harder, and are less effective at trapping contaminants. According to Energy Star, filters should be changed at least every three months and when they appear dirty. Check the filter's directions for the exact specifications.

Fiberglass furnace filters are affordable and adequate. Pleated filters are more efficient, but check the furnace’s owner’s manual to identify which air filter MERV rating is compatible with your furnace. High-efficiency filters can strain some systems.

Flip the furnace switch to turn off the furnace’s power before changing the filter. Filter location and orientation differ from furnace to furnace. Be sure you know which way the furnace filter goes because it could strain the system if it’s installed backward.

man changing dirty furnace filter

2. Inspect Burner Flames

Gas is ignited in the furnace’s burners to produce heat. Furnaces typically include a window in the access panel to inspect the flames’ color and intensity while the furnace runs. The flames are supposed to be steady and blue. Orange, yellow, or flickering flames indicate incomplete combustion due to dirty burners, insufficient air supply, or a cracked furnace heat exchanger. Changes in flame color and intensity can also reveal the presence of poisonous carbon monoxide.

3. Vacuum Inside Furnace

Ensure the furnace’s power is turned off, and remove the cabinet’s access panel—vacuum dust and dirt from the base around the burners with a shop vac hose. Avoid bumping the internal components, especially the ignitor. Look for sooty residue as you clean, which might indicate furnace issues.

To reach the backside of the burners, make an extension hose with an extra drain line. Attach approximately 20 inches of drain line to the end of the vacuum hose with duct tape.

The blower is typically located in the lower section of the furnace. Open the lower panel, and vacuum dirt and debris around the base of the blower.

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4. Clean the Blower

The blower motor and fan circulate air from the furnace through the ductwork. The blower motor assembly is commonly called a squirrel cage because it resembles a hamster wheel. Cleaning the blower requires the removal of the blower assembly. Be extremely careful or forgo this cleaning task; the fan can quickly become unbalanced.

Ensure the furnace’s power is turned off, and open the lower access panel. In some furnaces, the control panel blocks access to the blower. Loosen the screws on the control panel, and let it hang out of the way.

The blower is likely held in place by two bolts. Unscrew and remove the blower with a 7/16-inch socket and ratchet. After you’ve removed the blower, carefully remove dirt from the fan blades with a vacuum and a small brush. Avoid the fan’s counterweights and the motor’s wiring. Replace the blower and control panel when finished.

5. Clean the Flame Sensor

The furnace flame sensor is a safety device that ensures flames are coming from the burners when the gas valve is open. The sensor resembles a small metal rod that extends over the burners. Flame sensors can be straight rods or bent. Due to their proximity to the burners’ flames, flame sensors become coated with soot and residue. Dirty flame sensors malfunction and prevent the furnace from heating.

Ensure the furnace’s power is off, and remove the access panel. Unscrew and remove the flame sensor from its housing. Detach the sensor from its wires for easier cleaning. Scrape off any residue with a scouring pad, fine-grit sandpaper, steel wool, or the straight edge of a knife. Avoid using highly abrasive materials that scratch the metal, and do not rub the porcelain coating at the end of the rod. Wipe the rod clean with a rag. Reattach the wires, and replace the flame sensor.

dirty furnace flame sensor

6. Dust the Pilot Light/Hot Surface Ignitor

Older furnaces use a pilot light to light the burners. Newer furnaces use electronic ignition systems, such as hot surface ignitors or intermittent pilots. Dirty pilots and ignitors prevent the furnace from cycling on.

Ensure the furnace’s power is off, and remove the access panel. Use a drinking straw to blow away dust around the pilot or ignitor. Do not touch a hot surface ignitor; they are very fragile.

7. Lubricate Bearings

The blower motor’s bearing should be lubricated regularly for smooth operation and to prevent wear and tear. There are typically two motor bearings and two shaft bearings.

Ensure the furnace’s power is off, and remove the lower access panel. Older furnaces have oiling ports. Remove the oil caps, apply two or three drops of lightweight machine oil to each port, and replace the caps. For a new furnace, apply the oil directly to the motor shaft, where the rod attaches to the motor body.

8. Scan for Corrosion

Furnaces can corrode as they age. While the furnace access panels are removed to perform other maintenance tasks, scan for rust and a white, powdery substance that could indicate corrosion.

9. Clean the Drain Pipes

The condensate line drains away moisture from the furnace and air conditioner evaporator. It is typically a white pipe on the side or front of the furnace that leads to a floor drain.

Ensure the furnace’s power is off. Check the end of the pipe near the drain for blockages, and remove them with a rag, brush, or shop vac. Scan the length of the tube for cracks. Locate the opening to the condensate line, typically a T-joint with a plastic cap. Remove the lid, and flush the line with one cup of white vinegar to remove clogs. Let it sit for 30 minutes, then rinse it with plain water. Replace the cap.

clogged condensate pipe on furnace

10. Seal Leaky Air Ducts

Damaged, rusted ducts and unsealed seams allow air to escape and enter the ductwork. Duct leaks cause heat loss and can lead to mold growth. According to Energy Star, leaky ducts can reduce heating and cooling system efficiency by as much as 30 percent. Examine the ducts for leaks, and seal them with metal tape or heat-resistant silicone.

11. Adjust Dampers

Two-story homes with heating and air conditioning often have separate supply ducts with dampers to control the flow of air and temperatures throughout the house. Since hot air rises, the upstairs damper should be closed in the winter and open in the summer.

12. Test the Smoke Detector and Carbon Monoxide Detector

Smoke detectors detect smoke from fires. Carbon monoxide detectors detect the presence of carbon monoxide (CO), a deadly, odorless gas that might be released into a house from a malfunctioning furnace. Some sensors detect smoke and carbon monoxide. Smoke and carbon monoxide detectors have batteries that must be replaced regularly. The detectors have lifespans of five to seven years and must be replaced periodically.

Test the home’s smoke and carbon monoxide detectors, and replace the batteries if they haven’t been replaced in the last six months. Replace sensors that are more than five years old

13. Schedule Regular Maintenance Checkups

Professional furnace maintenance checkups are recommended once a year before the heating season begins. Professionals perform tasks that homeowners are not trained to perform, like testing electrical components, calibrating the thermostat, inspecting the heat exchanger, checking the venting, and replacing faulty components.

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When It’s Time for a Professional Furnace Tune Up

A DIY furnace tune-up is sufficient if you don't have the time or money. It’s certainly better than neglecting your furnace. However, specific issues should be addressed by professionals:

  • Abnormal burner flames

  • Soot deposits

  • Short-cycling or constantly cycling

  • The house is not warming up when the furnace is running

  • Poor airflow

  • Unexplained high energy bills

  • Strange odors

  • Strange noises

  • Water leaks

  • Cracked heat exchanger


Furnace tune-ups increase furnace performance and lifespan. Maintained furnaces are safer, less likely to break down, and more energy efficient. You might even lower your energy bills by maintaining your furnace. Homeowners can perform many of the maintenance tasks that furnaces require, but DIY tune-ups are not substitutes for professional inspections. Yearly professional inspections are recommended for optimal furnace performance.

Frequently Asked Questions

How often should I do a furnace tune up?

Furnace tune-ups should be performed at least once a year, in autumn. Ideally, the furnace should be tuned up twice a year, in the spring and fall, since the furnace contains some air conditioner components. Air filter changes should occur regularly, at least every three months.

How much does a furnace tune up cost?

According to HomeGuide, a furnace tune-up costs $70 to $200 and includes an inspection, cleaning, and testing of the furnace.

Are furnace tune ups worth it?

Furnace tune-ups are worthwhile. Tune-ups increase energy efficiency, lower energy bills, and reduce the likelihood of significant repairs, gas leaks, and carbon monoxide poisoning.


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