My Heater Won’t Turn On! Tips and Advice from the Pros

This article was crafted with the help of Pat and Steve Nugent from John Nugent & Sons.

After months of inactivity—and perhaps too little attention paid to seasonal maintenance—it’s common for heaters to malfunction when turned on in the winter.

Brothers Pat and Steve Nugent of Virginia-based John Nugent & Sons point out that a lack of maintenance is the root cause of many heater problems. They add that malfunctions sometimes result from user error or other minor problems that homeowners can resolve themselves.

Pat and Steve encourage homeowners to learn a little about their HVAC system so they’ll know when to implement a quick fix and when to enlist the help of a contractor.

Ready to learn some furnace troubleshooting tips from the pros? Keep reading!

Before You Call a Professional

When the heater malfunctions, Pat and Steve say there’s a list of things you can check yourself before calling a trained technician. Even if the following strategies don’t work, at least you’ll have covered the basics before enlisting professional help (and you’ll know what the problem isn’t).

Make sure the thermostat has batteries and is set correctly

If you’ve used analog thermostats for decades, you may be surprised to learn that your new digital thermostat requires batteries. If the thermostat is totally unresponsive, check the owner’s manual for instructions on changing the batteries and other troubleshooting tips before calling a pro.

Pat adds, “A lot of times, people accidentally hit the wrong button on the thermostat—either they hit ‘Cool’ when they meant ‘Heat,’ or they’ve just turned on the fan, not the heater.”

Check the air filter

Changing the air filter is the easiest maintenance task to perform and also the easiest to forget, which can lead to several different problems. “Homeowners should always check their filter,” says Steve. “A dirty filter can be the cause of issues like poor airflow—even to the point where the unit overheats and shuts off.”

If your heater turns on but produces tepid air or turns on and off intermittently, the filter may be so dirty that it’s interfering with normal operation. Inspect and change the air filter, and then consult a professional to confirm the heater didn’t suffer any lasting harm.

Check the circuit breaker and the emergency shutoff switch

If the furnace doesn’t seem to be getting power, the circuit breaker may have tripped.

Pat and Steve say that while you can reset the breaker yourself, you should be aware that a repeatedly blown breaker indicates a more severe problem—perhaps the blower motor going bad.

If the motor restarts after the breaker’s been reset, Pat and Steve recommend keeping an eye on the unit until it’s been serviced, making sure not to leave it on while you’re out of the house.

When the heater won’t turn on, it may also mean that the emergency shutoff (a switch near or on the unit that resembles an ordinary light switch) is simply switched off. This common oversight can be easily resolved by flipping the switch to “ON.”

Turn the power off and on

Advanced thermostats can lock out users if the diagnostic system detects a problem with the main unit. When that happens, Pat recommends shutting off power to the unit and then turning it back on again. “If it restarts and keeps running, that doesn’t mean you shouldn’t have a qualified technician check it out, but at least it’s working temporarily,” he says. “If it immediately goes back into lock-out mode, contact a technician right away.”

Problems to Leave to a Professional

Unfortunately, not every problem can be tackled without the help of a professional. Luckily, Pat and Steve provide additional helpful information for identifying more complex problems and working with your technician to resolve them.

If you encounter one of the following issues, Pat and Steve recommend getting in touch with a reputable HVAC contractor, not only for the most efficient and effective solution, but also in order to keep your unit operating safely and prevent permanent damage.

Gas furnace burners don’t light

Heaters with standing pilot lights that can be blown out by drafts are increasingly rare these days—they’re simply less efficient and safe than units with electronic ignitions.

However, electronic ignitions such as surface igniters or spark ignition systems can also have problems, usually as a result of age or lack of maintenance. If the burners on your gas furnace simply don’t light, the problem may be a dirty ignition.

A technician can solve the issue by cleaning or replacing the part.

Gas furnace burners light but go off quickly

Gas furnaces include flame sensors, safety devices that shut off the gas when no flame is detected. Once again, age or lack of maintenance can make a flame sensor malfunction, causing the burners to shut off right after lighting.

The problem can often be resolved by removing and cleaning the part.

Excessive frost or ice on a heat pump’s outdoor unit

A heat pump’s outdoor unit tends to collect frost in the winter, but the device has a defrost mode to prevent ice buildup. Excessive frost or solid ice indicates a malfunction.

According to Steve, “The unit goes into defrost mode about every 90 minutes or so. If it doesn’t and starts to freeze, it’ll cost a lot more to heat your house and ultimately damage the heat pump.”

A failure to defrost properly is likely not a problem you can tackle alone, so if your heat pump begins blowing cool air in the winter, check for ice on the outdoor unit and consult a professional.

Seasonal Maintenance and Safety

Pat and Steve reiterate that if you haven’t had your HVAC unit regularly maintained by a professional, don’t be surprised when you have a hard time turning your heat on in the fall or winter.

Changing the filters on a forced-air system, switching a heat pump from cool to heat as the season changes, and bleeding excess air from a boiler are all jobs that a professional can complete as part of a service agreement, with little hassle for you.

Pat adds, “When your technician is at your house, feel free to stand around and ask questions so you know a little more about your system. We encourage people to do that.”

On a final note, Pat and Steve urge every homeowner, especially those in homes with a fuel-burning appliance, to install a carbon monoxide detector. A faulty boiler, cracked heat exchanger, or plugged-up chimney all have the potential to send carbon monoxide into the house.

“Having at least two carbon monoxide detectors is a good idea,” advises Steve. “Manufacturers usually recommend putting one just outside the furnace room and one close to the bedroom, so it can wake you up.”

If the alarm goes off, Pat and Steve say that your immediate response should be to open the windows, get everyone out of the house, and call the fire department. “Every so often,” says Pat, “you’ll get a false positive. But you’d rather make a big deal out of it than put your family at risk.”

The Bottom Line

If you turn on your heater and nothing happens, don’t despair; the problem may be one you can solve yourself. If not, a qualified technician can provide a one-time solution, and regular maintenance will help prevent problems in the future.

During the technician’s visits, take Pat and Steve’s advice to ask questions and become as well educated as you can about your heater. Something you learn may prove vital if your unit has a problem later on.

Most HVAC system manufacturers and technicians recommend a minimum of two routine service visits per year: one in the fall, just before the weather starts to get chilly, and once again in the early spring before A/C becomes non-negotiable.

When you work with a Best Pick HVAC company like John Nugent & Sons, you can rest assured that you’re getting the best of the best. All Best Pick companies are fully vetted on an annual basis for quality service and customer satisfaction—and we verify state-required licenses and insurance every year, too.

If you’re ready to have your air conditioning and heating system serviced by a pro, give a Best Pick expert a call. You’ll be pleased with your experience—we guarantee it!

This spotlight article was crafted by John Nugent & Sons, an Air Conditioning & Heating Best Pick in Virginia. While we strive to provide relevant information to all homeowners, some of the material we publish may not pertain to every area. Please contact your local Best Pick companies for any further area-specific advice.