When your furnace is running but blowing cold or unheated air, the issue is usually caused by a dirty air filter, a tripped safety switch, or a failed ignition component.
An improperly set thermostat can stop the heating cycle from starting, while a clogged filter may cause overheating that shuts down the burners. Ignition-related problems, such as a faulty ignitor or contaminated flame sensor, can also prevent the burners from producing heat even though the blower continues running.
Reset the Furnace
Turn the thermostat to "OFF." Locate the power switch on the furnace (often looks like a light switch) or the circuit breaker. Turn it off for 30 seconds, then flip it back on. Turn the thermostat back to "HEAT."
Airflow Problems That Prevent Warm Air From Reaching Rooms
Restricted airflow is one of the most common reasons a furnace works hard, but rooms still feel cold. When air can't move freely through the system, the heat produced in the furnace never reaches your living space.
To get your furnace to kick on, first verify your thermostat is set to "Heat" and raised at least 5 degrees above room temperature. Next, check that the furnace power switch (usually resembling a standard light switch on or near the unit) is toggled "ON".
Yes, most furnaces have a built-in reset button to protect the system from overheating or other electrical faults. It is usually a small, brightly colored (red or yellow) button.
A frozen pipes furnace failure can cause major problems inside your home. Ice builds up fast in unheated spaces, and when frozen water expands, it can burst pipes wide open. That kind of mess is the last thing anyone wants during a winter heating outage.
5 Warning Signs It's Time for Furnace Replacement
To reset a furnace blower motor, turn off power to the furnace using the emergency switch or the circuit breaker. Wait 2-3 minutes, then locate the red or yellow reset button typically found on the blower motor housing. Press it firmly, and restore power.
The heat exchanger is often considered the most costly part of a furnace to repair or replace. It is a critical component that transfers heat from the combustion process to the air that circulates throughout your home. Over time, heat exchangers can crack due to the constant heating and cooling cycles they undergo.
To reset your furnace, start by turning off the circuit breaker and furnace power, wait about 30 seconds to a minute, then turn the power back on. If your furnace uses gas, you may also need to turn off the gas for a few minutes before turning it back on.
If your furnace is blowing cold air, the most common causes are a dirty air filter, incorrect thermostat settings (fan set to "ON"), or a pilot light that has gone out.
The reset button's location depends on your thermostat type. For older models, it is usually a recessed button on the circuit board (often behind the faceplate) or a dedicated button on the front or side. For modern smart thermostats, you typically reset the device through the digital menu.
Yes, you should turn the furnace off if it is continuously blowing cold air. Turning it off prevents the system from blowing unheated air, stops it from wasting electricity, and prevents further damage to the unit if there is a malfunction.
The Furnace Won't Ignite: This is the most common and most telling sign. If the gas valve doesn't open, the ignition sequence simply can't begin. Intermittent Heating or Sudden Shutdowns: These unpredictable cycles often point to weak solenoid coils or unstable electrical connections.
The $5,000 rule is a guideline to help homeowners decide whether to repair or replace their HVAC system. You multiply the age of your unit by the cost of the needed repair. If that number exceeds $5,000, replacing your HVAC system is often more cost-effective.
All furnaces are equipped with a reset button. They are generally red or yellow and are located inside the blower compartment. The reset button is a safety feature that will shut down the furnace when a problem is detected, often a hot or overheating furnace, before it trips the circuit breaker.
Diagnosing a faulty blower motor versus a bad resistor typically comes down to what fan speeds are working. If the fan only works on the highest setting, the resistor is usually the culprit. If the fan doesn't work on any speed, or if it makes strange noises, the motor itself is likely failing.
How to Stay Warm if Your Furnace Breaks
Short cycling
This is one of the most common furnace problems, and it can stress important furnace components such as the blower motor, limit switch, or flame sensor. There are several potential causes of short cycling, including some that are related to your furnace's built-in safety systems.
The Average Furnace Lifespan
A well-maintained furnace can last at least 15 to 20 years, but completing annual maintenance and being diligent with furnace repairs can extend its life even longer.
No, a standard gas furnace will not work without electricity. Even though they use natural gas or propane for heat, they rely entirely on electricity to power the ignition, safety sensors, control board, and blower motor.
As temps drop, the risk of having frozen pipes in your home increases. Typical high-risk areas for freezing include pipes within exterior walls, as well as exposed pipes that run through unheated or uninsulated areas such as attics or basements.
Focus on Safety and Immediate Comfort
Your first priority should always be the safety of you and your family. If the temperature inside your home starts to fall, gather everyone into one or two rooms to retain warmth. Make sure to close doors to unused spaces, add extra blankets, and dress in warm layers.
It's such a simple thing, leaving a single faucet dripping, but it can prevent so many complications later on. How much value does one dripping faucet have? A lot, if it keeps your home's water pipes from bursting during frigid weather.