Why is My Furnace Not Kicking on When the Temperature Drops?

Furnace Not Kicking On When the Temp Drops? Here’s Why

Are temperatures dropping, and your heat won’t turn on in the house? Whether you’re prepping your home for Amarillo’s cooler temperatures or your furnace isn’t performing how it should, some basic knowledge and easy fixes can get your furnace running smoothly. 

Furnaces are complex systems, but there are a few main reasons why your furnace won’t kick on when temps drop — check out these common causes and furnace troubleshooting methods below.

How Your Furnace Works

Your furnace uses combustion to heat your home, typically powered by natural gas, propane, electricity, or another fuel source. Whenever thermostat sensors detect that the indoor air temperature has dropped below your heat settings, it’ll notify your furnace’s control board and initiate the heating cycle.

The furnace ignites the burners, draws in cold air from your home, and warms it through the heat exchanger. As your furnace produces warm air, it distributes it through the ductwork to the vents in each room of your home.

7 Reasons Your Furnace Won’t Turn On

If your furnace doesn’t kick on when the temperature drops, it may point to a few different causes.

1. Thermostat issues

Since the thermostat is responsible for sensing temperature and communicating with your furnace, it’s the first place to look when your home’s furnace isn’t working. Besides your furnace not turning on, some signs of thermostat issues include:

  • Blank screen
  • No power
  • Unable to change settings
  • Thermostat continuously resets

Check that it’s loaded with fresh batteries, switched on, and set to heat, then verify that it’s set to the correct temperature. You may need to increase the temperature to initiate the heating cycle while you’re troubleshooting. 

If you have a programmable or smart thermostat, check that it’s programmed with the correct day, time, and schedule. If you have a pre-programmed heating schedule, match it to your household’s daily needs and routines to ensure it doesn’t stop the heating cycle from starting when you need it most.

2. Electric problems

Regardless of its fuel source, your furnace needs electricity to function. Check that the furnace’s power switch is on — it’s usually located on the unit or a nearby wall.

Inspect the breaker switch on your electrical panel to ensure that the furnace is receiving power. Short circuits, electrical surges, and other issues can trip the breaker, in which case the breaker switch will be in the center position. Switch it off and then on to reset it.

3. Pilot light or ignition problems

Furnaces manufactured before 2010 rely on a pilot light, which is a constant flame that ignites the burners. If the furnace is running but blowing cool air and the pilot light panel doesn’t show a blue flame, the light is likely out. In most cases, relighting the pilot light is a safe DIY task as long as you follow the proper precautions. Refer to the manufacturer’s instructions — or call Frank’s, and we’ll come out to light the pilot, day or night.

Modern furnaces use electric igniters to light the burners. Here are some signs of an igniter problem that requires professional service:

  • Your furnace repeatedly turns on and off, known as “short-cycling”
  • Cold air or no air is coming from the vents
  • Your furnace keeps tripping the circuit breaker
  • You hear a click, but the furnace doesn’t turn on

4. Gas supply issues

If your furnace runs on gas, several issues can prevent fuel from reaching the system, including a closed gas valve, an unpaid gas bill, or gas line work in the area. 

To check your furnace’s gas valve, locate it within six feet of the unit, attached to a gas pipe. The valve is either a small disk or a box with a lever. When the lever is in the “open” position, it’s perfectly parallel with the gas pipe. If the gas valve appears faulty or damaged, call Frank’s to schedule service — attempting to fix it on your own can be dangerous and void your furnace’s warranty.

If the valve is fully open, but you suspect there’s no fuel reaching your furnace, contact your utility company to verify your gas supply status.

5. A dirty filter or airflow obstruction

The air filter in your furnace traps dust and contaminants that enter the system to maintain air quality, but if debris accumulates and clogs the filter, it can cause the furnace to overheat.

Most air filters need to be replaced every 30 to 90 days. Locate the air filter in the blower compartment, which lies between the cold air return duct and the furnace itself. Slide out the old filter and replace it with a new one. Take note of the model number and size of the older filter, and stock up on replacements.

If a filter replacement doesn’t improve airflow, check the vents and ducts to make sure the dampers are open and free of obstructions like furniture or drapes. If you notice holes or blockages inside your ducts, contact Frank’s for duct repair or cleaning services.

6. Overheating and safety features

Whether due to poor airflow or malfunctioning parts, an overheating furnace can trigger the high-limit switch, which is one of several safety mechanisms that can shut down your furnace.

Triggering the flame sensor, which detects flames from burning gas, can also cause the control board to shut off the gas valve and burners. Likewise, the pressure switch triggers to prevent exhaust fumes from back-drafting into your system, guard against gas leaks, and stop the furnace cycle in case of mechanical failure. 

Most furnaces also feature a safety switch that stops the furnace cycle when the front panel door is ajar. Since several underlying problems can trigger safety features, it’s best to call in a furnace repair professional if you suspect any issues. 

7. Malfunctioning blower motor

Weak or no airflow, high energy bills, overheating, and a noisy system can indicate an issue. Wear and tear can cause the motor to malfunction, but debris buildup and clogs due to a dirty filter can also reduce the blower motor’s lifespan.

In many cases, simply replacing the motor’s belt or adding some lubricant is all the repair needed. Otherwise, it might be time to replace the motor — your HVAC professional can make the best call for your system.

What to Do If Your Furnace Stops Working

Furnaces involve a lot of complex mechanisms, and DIY troubleshooting when your furnace won’t stay on will only get you so far. If your furnace stops working and you’ve checked everything you can, it’s time to call in a pro.

The certified HVAC technicians at Frank’s have the expertise, experience, and the right equipment to perform emergency heating system repairs to get your furnace up and running again in no time.

How to Prevent Furnace Breakdowns

Furnace breakdowns are inconvenient and expensive — and they always seem to happen during the coldest weather, usually due to the extra demand. Lack of routine maintenance is a common cause of furnace breakdowns, which means they can be avoided with a little care.

To keep your furnace running smoothly during the heating season, schedule annual preventive maintenance in the fall. Check your air filter each month, and replace it when it’s dirty — typically every one to three months.

Need Furnace Repair Near Amarillo?

If you live in the Texas Panhandle, it’s important to be prepared for severe storms or sudden blizzards. With basic mechanical know-how, you can troubleshoot your furnace and determine if you need to call in a professional. 

In the meantime, annual preventive maintenance on your furnace in the fall will help you stay ahead of repairs and reduce the chances of the heat not working in your house when you need it the most.

Frank’s Repair Plumbing provides around-the-clock emergency furnace repair — all of our HVAC technicians are NATE-certified and state-licensed, and they’re a friendly, professional bunch. That’s why Frank’s has been voted Best of Amarillo for 17 years and counting — we’re your go-to local HVAC service provider, with more than 70 years of experience doing business in the Texas Panhandle. Contact us today, and enjoy the highest level of home comfort in all seasons.