Many homeowners may not notice furnace problems until the temperature drops. If you turn up the thermostat but notice the furnace not turning on, you can try several solutions before having to call an HVAC technician. Take a look at the most common issues that cause a furnace to not turn on and possible solutions from El Cajon’s furnace repair company.

1. Thermostat Problems

Your thermostat tells your furnace how warm you want your home and when the room temperature has reached your desired setting. Problems with your thermostat can cause your furnace to not respond when your interior air begins to cool. Thermostat issues can include:

The Wrong Settings

Check your thermostat and make sure that you have it set to the “heat” setting and have the temperature set above the current temperature in your home.

Failing Batteries

While modern thermostats might tell you when their batteries get low, older models don’t have the technology to warn you. Replace your thermostat’s batteries and reset the temperature to see if that turns your furnace on.

Bad Wiring

Thermostats use complicated wiring systems to connect with your HVAC unit and properly relay temperature data. Normal wear and tear, improper installation, or a damaged thermostat box can all cause problems with the wiring.

Because thermostats have such delicate systems, homeowners should leave repairs up to the professionals. Trying to fix your own thermostat can cause further damage.

2. Gas Flow Issues

Gas reaches your furnace through a valve that homeowners can switch on and off. Most gas valves look like boxes or levers, but all of them will have a handle that you can twist to open or shut the valve. Checking your gas flow can help you determine if your furnace receives enough gas for the pilot light to stay lit.

Check the Furnace’s Gas Valve

Some gas valves stick out, making them easy to accidentally kick or hit. When on, your gas valve’s handle will run parallel to the gas pipe, while a handle running perpendicular indicates that your gas is off. Open the closed valve and wait to see if that helps your furnace kick on.

Check Gas on Other Appliances

If your furnace still doesn’t turn on, check other appliances that use gas to see if they turn on. If not, you may need to see if your home has gas coming in at all.

Check Interior and Exterior Valves

Homes using gas will have an interior valve and exterior valve. Each of these is a safety mechanism in case you have a gas leak. Make sure that both valves stay open, then try turning on your gas appliances and furnace again.

3. Blocked Air Flow

Sometimes a furnace not turning on just needs an air filter change. Air filters collect lint, dust, and other debris that can eventually stop air from reaching your furnace and cooling down its mechanisms. As the furnace’s heat exchanger increases in temperature, the limit switch shuts the furnace down to avoid causing fire or explosions.

Furnace filters require replacement every one to three months depending on how often you use your furnace, how many people live in your home, and whether you have pets. If you change out your filter and your furnace still won’t turn on, the problem may lie in your ductwork. Look inside your home’s vents to ensure that the ductwork hasn’t collapsed or disconnected.

If you see any gaps, holes, or other damage in your ductwork, you can use duct tape to temporarily seal them until you can have a professional work on them for you.

4. Pilot Light Problems

If your furnace makes a clicking sound like it’s trying to light but can’t, you may have an issue with the pilot light or ignition sensor. You can remove and clean the sensor with these steps:

  1. Turn off your furnace’s power switch, then shut off the gas valve.
  2. Using a screwdriver, remove the sensor. The entire piece looks like a porcelain base with a thin metal rod sticking out of it.
  3. Gently scrub the rod with steel wool, ensuring you don’t separate the rod from its base.
  4. Wipe the whole sensor down thoroughly, then place it back and turn on the gas.

If none of the prior steps turned your furnace on, you may need to call a professional for furnace repairs.

5. Furnace Malfunctions

Furnaces have many working parts that rely on one another, meaning that if one component fails, it can kill the appliance’s functionality. In many cases, a broken furnace requires professional HVAC service to troubleshoot and repair the problem. Common furnace malfunctions may include:

Failing Blower Motor

Your furnace uses the blower motor to propel warm air into your air vents, so a dead blower means that the generated heat doesn’t go anywhere. As the heat rises inside the unit, the furnace shuts itself off to avoid overheating.

Damaged Heat Exchanger

Heat exchanger tubes heat the air as it goes through your furnace, but these sensitive parts require regular maintenance. While manufacturers build exchangers to handle a high amount of heat, they may still crack or break if not cleaned often enough.

Constantly Tripping Circuit Breaker

A furnace that constantly trips your circuit breaker indicates an electrical problem. Something in the furnace itself could cause power surges or interruptions, or the main electrical wiring leading to or from the furnace could have a short. 

In any situation where your furnace not turning on looks like a problem with the furnace itself, you should keep yourself and your home safe by calling for professional furnace repair.

Stay Warm All Winter Long with Furnace Services by Maximum Comfort Heating & Air Conditioning in El Cajon, CA

When winter weather comes along, everyone wants to keep their homes comfy and warm with a properly working furnace. Learn the answers to “Why does my furnace smell like burning?” from El Cajon’s top HVAC specialists.

If you notice your furnace not turning on in your El Cajon, CA, home, call Maximum Comfort Heating & Air Conditioning at (619) 949-1379.

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