If you turn your furnace on for the first time this fall and suddenly smell something burning, there is a good chance you are simply smelling dust that has accumulated inside the heating system during the spring and summer. This is very common when a furnace has not operated for several months.  As your furnace heats up, dust that has settled

If your furnace filter seems to get dirty much faster than it should, there is usually a reason. A furnace filter is designed to capture dust, pet hair, pollen and other airborne particles before they circulate through your heating and cooling system. Some buildup is normal. But if the filter becomes heavily coated after only a few weeks, your furnace

If your furnace makes a loud bang, pop or booming sound right after it shuts off, the noise may be coming from the furnace itself or from your home’s ductwork. One of the most common causes is sheet-metal ductwork expanding and contracting as it heats up and cools down. But a loud bang can also be related to airflow problems,

If your furnace turns on, runs for only a short time, then shuts off before your home reaches the temperature set on the thermostat, it may be short cycling. Short cycling means the furnace is starting and stopping more frequently than it should.  Sometimes the cause is simple, such as a dirty filter. In other cases, it can point to

If your gas furnace starts normally, the burners ignite and then the flame shuts off a few seconds later, the flame sensor may be dirty or failing. The flame sensor is a small safety component that confirms the burners have actually ignited. If it does not detect a flame, the furnace shuts off the gas supply to prevent unburned gas

If your furnace tries to start several times and then stops working altogether, it may have gone into lockout. Furnace lockout is a safety feature. When the furnace detects that something is preventing it from starting or operating correctly, the control board may stop additional ignition attempts. Depending on the furnace, it may try again after a certain amount of time,

If your furnace keeps trying to ignite but never starts properly, or if the burners light briefly and then go out, there is usually a problem somewhere in the ignition or safety sequence. A gas furnace has to complete several steps before it can begin heating your home. If one of those steps fails, the furnace may stop, wait, and

If your furnace igniter glows red or orange but the burners never light, the furnace is making it partway through the startup sequence but something is preventing ignition. A glowing igniter tells you that the furnace is receiving a call for heat and that at least part of the ignition system is working. But the furnace still needs the proper

If your furnace clicks when the thermostat calls for heat but never actually starts, the system may be attempting to begin its normal startup sequence and failing somewhere along the way. The clicking sound may come from the thermostat, control board, gas valve, igniter or another electrical component. What happens immediately before and after the click can help narrow down the cause.

If your furnace burners ignite but then go out before your home reaches the temperature set on the thermostat, something is interrupting the heating cycle. The cause could be as simple as a dirty flame sensor, but repeated burner shutdowns can also be related to overheating, airflow problems, ignition issues, venting problems or a failing furnace component. The timing of the shutdown

If your furnace is running but the air coming from the vents feels cold, the system may not be completing the heating cycle properly. Sometimes the cause is simple, such as a thermostat setting or dirty filter. In other cases, the furnace may have an ignition problem, flame sensor issue, airflow restriction or another problem that is shutting the burners off.

If your furnace starts heating normally but shuts off before your home reaches the temperature set on the thermostat, something may be interrupting the heating cycle. A dirty filter, overheating furnace, thermostat problem, flame sensor issue or airflow restriction can all cause this symptom. The important distinction is that the furnace is stopping even though the thermostat is still calling for

If your furnace has a red light flashing inside the cabinet, it is usually trying to tell you something about the condition of the system. Many modern furnaces use a small diagnostic LED on the control board. The light may stay solid, blink slowly, blink rapidly or flash in a repeating pattern. The exact meaning depends on the furnace manufacturer and

If your furnace stops heating properly and a light on the control board begins flashing, the furnace may be displaying an error code. These codes are designed to help identify where the system detected a problem. The important thing to remember is that furnace error codes are not universal. A code that means one thing on a Carrier furnace may mean

If your furnace blower keeps running after the burners shut off, that does not always mean something is wrong. In many systems, the blower is designed to continue running for a short time after the heating cycle ends. This helps move the remaining warm air out of the furnace and through the ductwork. The concern is when the blower runs much longer