Furnace Not Turning On? Here’s A Troubleshooting Guide

From basic checks to gas furnace repair, here’s what you need to know!

We know it all too well: that sinking feeling you get when you realize your furnace is no longer working. In the midst of winter, it can ignite panic. That is, if you don’t know what to do. If you do know what can be done about the issue, though, the situation can downgrade from “end of the world” to “annoying inconvenience.” So if you discover a furnace not turning on, a little knowledge can go a long way. Here are some tips and insights that can help!

Check the Basics First

So you just discovered the issue. No need to turn to in-depth furnace troubleshooting just yet. Many heating issues are caused by (relatively) simple issues. So before you go into emergency mode, check the following:

Thermostat Settings

Is your thermostat set to “heat”? If not, problem solved. Simply change it over and set it a few degrees higher than the room’s current temperature to test it out. If it’s set to “heat” and still not functioning properly, check its batteries. Low batteries may provide enough power to turn on the screen, but they may make it seem like your furnace not turning on is a bigger issue than it actually is. Better to check this before spending a lot of time and money on a fix.

Power Supply

Next, you should make sure the furnace itself has power. Locate the power switch (generally located on or near the unit) and make sure it’s in the “on” position. If the problem persists, check your electrical panel for a tripped breaker that could be the cause of your furnace not turning on.

Gas Supply

If your system is gas-based, ensure the valve is open. In the hustle and bustle of moving and storing things around your unit (especially during the recent holidays), it’s possible the switch was bumped on accident.

Safety Tip: If you smell gas during this check, leave your home right away and call your gas company. Do not attempt further troubleshooting until the issue is resolved.

Common DIY Checks

Say you’ve done all the basics above and your system is still being stubborn. What now? There are still a few DIY-friendly steps that could solve the problem without having to call the pros.

Replace the Air Filter

Airflow really matters. When it has nowhere to go due to a clogged filter, the unit can stall in order to protect itself (and you). Pull out the filter and give it a good examination. If it looks dirty, replace it and try your furnace again. You’d be surprised how common of a culprit this is.

Inspect the Pilot or Ignition

If your system is old, it likely has a pilot light. Following the unit’s instructions, reignite it and see if that resolves the issue. If your system is newer, however, it likely relies on an electronic igniter. If this is the case for you, it isn’t a quick DIY fix.

Look for Error Codes

Modern systems have quality LED displays that will alert you if you need gas furnace repair or require any kind of furnace troubleshooting. They will point you towards potential issues with ignition, sensors, and even safety switches, so read them carefully and act accordingly.

When It’s NOT a DIY Fix

Unfortunately, if you notice your furnace not turning on, the issue could require solutions that aren’t suited for DIY efforts. After all, there are many internal components that need to be handled delicately, meaning a professional should be the only one for the job. With that in mind, here are some common issues that definitely shouldn’t be done by someone who isn’t qualified.

• Ignition system or flame sensor failures: Electronic igniters eventually burn out, while flame sensors can become dirty and experience issues. Replacement of either one requires a certified gas furnace repair technician.

• Blower motor or fan problems: If the blower isn’t running, the furnace may fire up and shut down shortly thereafter. Whether it’s a motor, capacitor, or belt, they’re all firmly in the “call an expert” category of issues.

• Limit switch or safety controls shutting down the system: Built-in safety controls are a feature of modern furnace units. They’re meant to prevent overheating and other dangerous conditions, and tinkering with them shouldn’t be handled by the homeowner.

• Gas valve or control board malfunctions: These are essentially the furnace’s “brains.” Repairing or replacing them requires specialized knowledge that makes a DIY approach unfeasible.

Safety Considerations

Furnaces are designed with a wealth of safety features top of mind, but when it comes down to it, they’re still big pieces of equipment that present electrical or fire-related safety hazards if they’re mishandled. Keep these safety points in mind if you notice your furnace not turning on:

• Don’t try to brute-force mechanical parts, modify wires, or bypass safety switches.
• If you have a gas system, install a carbon monoxide detector in your home.
• Shut the furnace down and call for help if you notice unusual smells, smoke, sparking, or loud banging noises coming from your furnace.

Know When to Call Holtzople

If you’re still facing a furnace not turning on despite trying all the DIY tricks above, calling the pros is the wise choice. It’s a great idea to give us a call if:

• The unit isn’t starting after basic checks
• You’re experiencing short cycling or quick shutdowns
• You notice unusual smells or sounds
• Your system is more than 10 years old
• You need a quick solution without guesswork and uncertainty

We’re here for you when you’re experiencing an emergency failure in the middle of winter. It’s a situation that should be taken seriously, and we’ll commit our expertise to making sure you can get back to comfort as soon as possible. For any and all HVAC needs, get in touch and we’ll get your home comfort back on track!

For a quick “failing furnace” checklist, see below.

Troubleshooting Checklist

☐ Is the thermostat on “heat” and set above the current room temperature?

☐ Are the thermostat’s batteries fresh?

☐ Is the circuit breaker tripped?

☐ Is the furnace power switch in the “on” position?

☐ For gas furnaces, is the gas valve open?

☐ Is the air filter clean?

☐ Is the display indicating any errors?

For more on furnaces and why you should schedule regular inspections, check out our December blog.