6 Furnace Troubleshooting Tips So Good You Won’t Need to Call a Pro

Lydia Schapiro
Written by Lydia Schapiro
Updated January 19, 2022
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Take the heat off your HVAC pro—and back in your furnace

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No one wants to deal with a malfunctioning furnace in the icy winter months. Fortunately, you might be able to solve your furnace issue with these six tips before jumping the gun and hiring a furnace repair professional.

1. Change Your Air Filter

A functioning filter is crucial to extending your HVAC system life span since your furnace relies on a constant supply of clean air. Without it, your furnace can't correctly do its job.

If the filter is too dirty or clogged, it'll restrict the airflow and won't have enough air to supply throughout your home. In addition, a dirty air filter can cause the entire HVAC system to malfunction or result in an overheating furnace. If your filter is filthy, it can even cause the furnace to frequently turn itself on and off.

You can visually inspect your filter for dirt. If it’s dirty, replace the filter as soon as possible. You can also listen to your filter for signs of filter malfunction. If you hear a whistle, the furnace might be having trouble pushing all the air through.

Add inspecting your furnace filters to your home chores checklist, and aim to change your furnace filter every one to three months.

2. Check the Circuit Breakers

Another measure to take before calling in a pro is to check the circuit breakers. Sometimes, using too many appliances at once can cause breakers to turn off. First off, ensure the furnace’s circuit breaker is on. Sometimes, you may just need to turn it back on.

Check to see if the circuit breaker has tripped. You’ll know this has happened if it’s between the “on” and “off” positions. If this is the case, reset the breaker by turning it all the way off and then on again.

3. Inspect the AC Wires

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When your furnace doesn’t start, check the wires around your AC unit. These wires may be exposed and surrounded by furniture or various objects. As a result, they can disconnect from one another or get damaged. You may just need to reconnect the wires to one another.

4. Check the Batteries

Sometimes, a furnace that won’t turn on simply needs new batteries. Usually, furnaces using batteries have a low-battery indicator that’ll flash if it’s time for a replacement. If this is the case, you’ll need to do a battery swap.

5. Inspect the Gas Valve

A check-in on your gas valve may solve your furnace issue. The gas valve is the furnace component that manages the gas flow within the system. This valve should always be in the “On” position.

The gas valve is located near the pipe that runs into your home. You’ll have to find the gas line outside (attached to your house) and follow it to the valve, which will be perpendicular to the pipe.

6. Look for a Code

With all the technological advancements we’ve seen in this lifetime, it might not seem that crazy that many modern furnaces can provide you with a code that diagnoses any given furnace issue.

If your furnace has this feature, you’re in luck. The code can provide you with useful information about its condition. Usually, furnaces will have a window where the code will pop up (in the form of a light) and indicate whether the furnace has power. In addition, the code will show the potential issue source.

To make it even easier, your furnace may have access panels that explain what your code means. If you ultimately can't fix the issue yourself, you'll still have helpful information to give to a top-rated HVAC professional near you.

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