How To Troubleshoot Your Furnace: A 10-Step Guide

A working furnace is key to keeping your home cozy during chilly months, but when it starts acting up, the frustration kicks in. Don’t worry! Many common furnace issues have simple fixes you can try on your own before calling in a professional. Use our 10-step guide to troubleshoot your furnace and save both time and money.

First, locate your furnace manual. If you can’t find the printed version, many furnaces now offer digital manuals that you can access using your furnace’s model and serial number. You can usually find this information in several places: on a data sticker on the left inside wall beneath the burner, on the rating plate on the inner wall, above the blower deck, or on the left side inside the top-front service panel.

Step #1: Confirm Your Thermostat Settings

Yes, it sounds simple, but always start here! Thermostat issues are one of the most common reasons for furnace problems.

• Set your thermostat to “heat,” and make sure it’s set higher than the current room temperature.
• If your thermostat runs on batteries, check or replace them.
• Some models may need a manual reset — grab that user manual for guidance.

Step #2: Make Sure the Power Is On

If your furnace isn’t turning on, it could be something as basic as a power issue.

• Check if it’s securely plugged in. (This sounds obvious, but it’s easy to overlook if you’ve recently cleaned or moved things around.)
• Head to the circuit breaker panel to see if the furnace breaker has tripped. Flip it back on if it has.
• If the breaker keeps tripping, or if it trips again right away, it’s likely a sign of a bigger electrical issue that requires a professional; call a trusted electrician.

Step #3: Inspect the Filter

An old or clogged filter can wreak havoc on furnace function. If the filter is clogged, it restricts airflow, which can make the furnace overheat and shut off as a safety precaution.

• Take a quick look. Is it dusty or clogged? Replace it immediately! Not only will your home’s air quality improve, but a clean filter will also protect your furnace’s efficiency.
• A good rule of thumb is to replace or clean your filter every one to three months. You’ll need to change it more frequently if you smoke, have pets or allergies, or live in an especially dusty area. Changing your filters more often will protect your airflow and air quality.

Step #4: Check the Pilot Light or Ignition

Older furnaces with pilot lights can sometimes go out.

• Check your furnace manual for instructions on safely relighting pilot light. Always turn off the gas supply first. Carefully relight the pilot light.
• For newer models with electronic ignitions, listen for a clicking sound. If no flame appears, the igniter may need replacing.

Step #5: Open Vents and Registers

Airflow is essential to your furnace working properly. Blocked vents and registers can cause uneven heating and cooling, forcing your furnace to work harder and increasing the risk of breakdowns.

• Walk through your home and ensure all vents are open and free from obstructions like furniture or curtains.
• Clear airflow means a happier furnace and consistent warmth.

Step #6: Test the Blower Motor

If the furnace turns on, but no warm air blows, the blower motor might be the issue. This component circulates air throughout your home, pushing warm air from the furnace through the ducts to maintain consistent temperatures.

• Check your furnace manual to locate the blower motor. Turn off the power, then check for dust or debris around the motor and clean it gently.
• If the belt or motor appears damaged, it’s time to reach out to a technician.

Step #7: Clean the Flame Sensor

The flame sensor is a tiny device inside your furnace that ensures a flame is present. A dirty flame sensor can shut your furnace down.

• Turn off the system and remove the sensor (your manual will show you how to do it).
• Gently clean the sensor with a soft cloth or fine sandpaper, then reinstall it.
• Once the sensor is back in place, see if your furnace starts running normally.

Step #8: Be Alert to Noises and Smells

Strange noises or odors coming from your furnace could be early signs of trouble.

• Noises like banging, rattling, or squealing indicate loose parts or a worn-out motor belt.
• When you first turn on your furnace after a break, dust on the heat exchanger and other parts burn off and give off a burning odor. This smell should fade quickly, so if it persists — or if you smell gas — turn off the furnace immediately and call a professional.

Step #9: Check for Duct Leaks

Leaky or damaged ductwork can cause uneven heating and drive up your energy bills.

• Inspect accessible ductwork for any gaps, holes, or loose connections.
• Seal small leaks with duct tape or a mastic sealant to keep warm air where it belongs — inside your home!

Step #10: Know When To Call a Pro

Sometimes, the best DIY rule is knowing when to call in a professional. Certain electrical issues can pose safety risks or fire hazards and are best handled by trained experts with the right tools to fix them safely.

• If none of these steps resolve the issue, or if you suspect gas line or wiring problems, don’t hesitate to contact a licensed HVAC technician.
• Regular professional maintenance helps catch problems early, preventing expensive repairs down the road. Furnace manufacturers recommend annual tune-ups to maintain your warranty and keep your furnace running smoothly.

4 Bonus Tips for Maximum Efficiency

While troubleshooting, keep these extra tips in mind for a cozier, more efficient home!

1. Upgrade to a smart thermostat for better control and energy savings. Switching to a programmable or smart thermostat allows you to set schedules, such as lowering the heat while you sleep or warming up your home before you wake up or return. Smart thermostats can even learn your habits over time to help save even more energy.
2. Seal drafts around doors and windows to prevent heat loss. Even with a great furnace, heat can escape if your home isn’t properly insulated. Check for drafts around windows and doors, and seal any gaps with weatherstripping or caulk. This quick fix can help retain heat and make your furnace’s job much easier.
3. Use ceiling fans set clockwise to circulate warm air back down. Ceiling fans aren’t just for summer! In the winter, set your fan to rotate clockwise at a low speed. This pushes warm air that rises back down into the room, helping spread the heat more evenly.
4. Keep the area around your furnace clutter-free for safety and ventilation. Consistently make sure that there’s no clutter — like boxes or furniture — around your furnace. Clear space helps airflow, reduces fire risks, and makes it easier for technicians to access the unit for repairs or maintenance.

Stay Warm With Advanced Home Services!

These 10 DIY steps can help you tackle common furnace issues to ensure a warm and cozy home this winter. But if your troubleshooting efforts don’t resolve the issue, we’re here to help!

At Advanced Home Services, we specialize in heating repairs, installations, and maintenance for gas, electric, and propane furnaces in Southeast Idaho. Our skilled technicians deliver prompt, reliable service backed by a 100% satisfaction guarantee. With years of experience and access to top-quality products, we’ll make certain that your heating system is ready to keep you and your loved ones comfortable all year.

Contact Advanced Home Services today to schedule your heating repair in Southeast Idaho!