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.
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.
Check Your Thermostat: If your furnace doesn't turn on automatically, the thermostat may have lost its programming or reset. It may even simply be set on the wrong setting. For test purposes, set your thermostat about 10 degrees hotter than the current temperature to see if the system turns on.
There could be several reasons for a central heating thermostat not functioning, such as: Power issue. Dead batteries. Incorrect settings.
Possible causes include a broken thermostat; the thermostat being set too low; an out pilot light; a blown fuse or circuit breaker; a closed gas valve; or electronic ignition problems.
If your thermostat won't turn on the heat in your home, change out the batteries and see if that fixes the problem. If not, your faulty thermostat could be the result of the following: A tripped breaker. Loose wiring.
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.
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.
There is usually a small reset button somewhere on the thermostat. Finding this button may require that the thermostat panel be removed and pressing this button may require something like a paperclip to push. Hold the reset button down for 5 seconds and the thermostat should reset.
Faulty Wiring or Equipment: Bad wiring can prevent power from reaching your thermostat. It can also increase the risk of a short circuit or fire. Check whether the thermostat's wiring is frayed, broken, or installed incorrectly (the wires/terminals are usually color-coded).
If nothing's happening when you're expecting the whir of a blower, check the circuit breaker and fuse. 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.
Check the circuit breaker panel.
The next simplest solution for a thermostat that has no power is a tripped circuit breaker. This is a common cause for appliances, power outlets, and HVAC equipment not working. Open your electrical panel and look for a switch that is not aligned with the rest.
The thermostat is the central control of your HVAC system, and malfunctioning can prevent the AC and furnace from turning on.
Standard thermostats: Enlist a friend or family member to assist, Position one person by the thermostat and one person by the furnace. Slowly turn the thermostat from off to heat and increase the temperature. Both the thermostat and furnace should make a sound.
If your thermostat is not working, change the batteries, make sure it is turned on, the thermostat is set to the correct mode, check the power supply and airflow.
Your thermostat is responsible for telling your furnace when to turn on and off. So if your thermostat is not set or working properly, it might never tell your furnace to kick on. The first thing you'll want to check is your thermostat's settings.
Clean your Air Filters, Vents, and Ducts – A clogged air filter will struggle to meet the thermostat's set temperature since the dirt and debris buildup prevents air from circulating through the vents. And as airflow into living spaces drops, so do comfort levels.
If the thermostat's display is dark, a lack of power may be the issue. Try replacing the batteries, then check for a blown fuse or tripped breaker in the electrical panel. If the thermostat is still unresponsive, make sure the breaker is shut off and remove the cover.
The average cost of a new thermostat, including installation, ranges in price from $50 to $500 or more based on several factors including the type of thermostat, labor costs, the complexity of the installation, and more.
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.
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.
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.
The Short Answer Is: Warning signs of a bad furnace ignitor include the furnace not starting or heating, a noticeable clicking sound without ignition, or frequent short cycling where the furnace turns on and off rapidly. Additionally, if the ignitor appears cracked or discolored, it may need replacement.