The cause of your furnace not blowing hot air could be the thermostat configuration, a dirty air filter, the high limit switch, a clogged condensate line, insufficient fuel, leaky ducts, ignition problems, a blocked burner, flame sensor issues, gas valve malfunctions, a cracked heat exchanger, or a clogged coil.
If your furnace doesn't switch on, the circuit breaker could be shut off. Check your circuit breaker panel to make sure all switches for your HVAC system are set to “ON.” Check Your Thermostat: If your furnace doesn't turn on automatically, the thermostat may have lost its programming or reset.
At your electrical panel, make sure all switches related to the HVAC system are on. Reset any tripped breakers and replace all blown fuses, and your furnace should kick back on. Gas supply leaks: If you smell gas, leave the area immediately and contact your gas company for emergency services.
A non-working furnace fan typically stems from electrical issues, mechanical failures, or control problems. Start troubleshooting by checking your circuit breaker, thermostat settings, and air filter condition.
If your furnace won't kick on when you turn the thermostat up, it could be due to a variety of reasons such as a tripped circuit breaker, a faulty thermostat, or a problem with the furnace itself like a malfunctioning igniter or gas valve. Checking these components might help you figure out the issue.
Checking your thermostat is the best place to start. Make sure it's set to “heat” and that you've set the temperature higher than the current room temperature. If that doesn't resolve the problem, try switching your fan to “on” to force the furnace to start working.
Check the Power Source Sometimes the problem between the thermostat and your furnace is as simple as replacing the batteries. Many digital thermostats use standard batteries to power their functions. Also make sure to check there is power at the furnace as well.
Inspect the wires in your furnace to ensure that the power cord hasn't melted or a fuse hasn't been blown. If the cables appear to be in good condition, try unplugging the fan for a few minutes and then plugging it back in again. This can sometimes reset the motor and resolve the issue.
The blower motor contains a capacitor, a device that stores energy to help the motor turn over with a jolt of extra electricity when it first starts up. If the capacitor goes bad, electricity may not reach the motor or it may not have enough electric to power the motor for its initial spin.
There are several reasons why your furnace may not turn on. The most common include a broken thermostat, gas line issues, clogged air filters, blocked ductwork, a tripped circuit breaker, and issues with the furnace itself.
If your heater doesn't start, chances are the problem stems from having a dirty furnace. Having dirt on your blower motor or flamer sensor could render your furnace unable to perform. When the blower motor is too dirty, it won't pass enough cool air to the heat exchanger, leading to equipment failure.
If your furnace won't come on, check the ignition sensor. A dirty sensor could be the reason why your furnace won't stay on or even why your furnace won't stop blowing cold air. Only if the furnace's heat exchanger — the part that actually heats the air — senses an ignition, will it power on the furnace.
Leave the breaker(s) off for at least 10 minutes while the system is off and “rebooting.” After 10 minutes have elapsed, go back to the breaker box and flip the HVAC breaker(s) back on.
One of the most common furnace problems is a malfunctioning thermostat. A sure sign your thermostat isn't working properly is if your fan is constantly running. This will cause your thermostat battery to run, and cause your furnace to work inefficiently.
The thermostat may have a dead battery, so replace them with fresh ones and try again. Your furnace may turn on right away after this. If it doesn't, you may have a faulty power circuit. Have an HVAC professional diagnose this issue, and provide you with professional recommendations.
Mind the safety lock. When resetting your furnace, make sure to press the button only once to avoid engaging the safety lock. Reach out to professionals. In most cases, the safest course of action is to contact your go-to HVAC company if your furnace doesn't work after a power outage.
When this occurs, often after two or three failed restart attempts, the furnace is known to be in lockout mode and will not attempt to run again until the furnace is manually reset. It is important to note that there are soft and hard lockouts, which does vary by manufacturer.
Troubleshooting your furnace blower when it's not working can be a step-by-step process: Check for Electrical Issues: Inspect the furnace circuit for blown fuses and reset circuit breakers if necessary. Inspect the Air Filter: Examine the air filter for debris and dust buildup and replace it if dirty.
To put it very simply, the furnace fan limit switch is a control that tells your furnace's fan when to turn on and off.
No power: If the thermostat isn't working at all, there could be a power issue. Try checking the circuit breaker box or replacing the batteries. Bad wiring: The thermostat may be unresponsive if the wiring has gone bad. Remove the cover and check inside for loose, detached, or corroded wires.
Most likely, your furnace is making a clicking noise and not providing heat because your furnace's spark igniter is trying to ignite your pilot light or burners but is failing to do so. In other words, there's an ignition system malfunction that needs to be fixed. Otherwise, your furnace won't start.
Furnace Not Igniting Because of Incorrect Thermostat Setting
Make sure the thermostat is set to heating and that the temperature is set high enough to actually turn the furnace on. It may be set at too low of a temperature to activate the furnace.