One of the most common issues is the thermostat. The wiring, switches, or
The short answer is your furnace won't turn off due to some kind of error or malfunction within your furnace, thermostat, or HVAC system. It could be the wrong thermostat setting is being used, a clogged air filter or your thermostat itself is no longer working properly.
It could (likely) be one of two things. Either the thermostat is sticking and not disengaging or you have a short in the wiring.
Check the ductwork.
As air flows through your ductwork, seals and joints loosen. That can create leaks. Other leaks may also develop. Leaky ductwork makes it hard for your furnace to reach and stay at your set temperature, meaning it will run longer and more often.
If the blower will not shut off that is either a stuck relay on the control board or if a thermal rollout on the unit has tripped open the board will tell the blower to run continously because it thinks it has overheated.
If your fan limit switch is set to AUTO but the fan continues to run without ever stopping, you'll need to call a professional. Two problems that could cause your fan to run without stopping include: A bad fan limit switch that needs to be replaced. Bad thermostat wiring.
Check Your Temperature Setting
If your thermostat won't turn off heat, check the temperature setting to the compare temperature. If it's greater than the room air temp, your furnace will keep operating until it reaches your desired temp.
As long as the furnace is running efficiently and not making strange noises, the constant operation is likely nothing to worry about. But in general, your furnace should not constantly be running. Otherwise, it could indicate a problem with your heating system.
Locate the sensor, which is a small, round component usually positioned near the bottom of the thermostat. It may be labeled as “sensor” or “thermistor.” Using a soft brush or a can of compressed air, carefully clean the sensor to remove any dust or debris that may have accumulated on its surface.
If your thermostat is not working properly, it may not be able to accurately read the temperature in your home or properly communicate with your furnace. This can cause your furnace to run continuously, even if your home is already at the desired temperature.
If your home radiators will not switch off even when the central heating isn't on, the most likely cause of the issue is troubles with a diverter or check valve. Should the valves become damaged or blocked, they can continue to transport hot water to your radiators even when the thermostat is switched off.
You could have a dirty air filter, clogged condenser coils, frozen evaporator coils, a broken relay switch, or a bad thermostat, amongst other common air conditioner issues.
Symptoms of a faulty diverter valve often include inconsistent hot water flow and radiators not heating properly. Homeowners may notice that radiators remain cold even when the boiler is on. Inconsistent water temperatures are common, with water switching from hot to lukewarm or cold unexpectedly.
Alternatively, you could attempt resetting the thermostat by turning it off and back on again. If all else fails, we suggest checking whether the batteries need replacing. If the batteries are weak then a simple replacement should solve the issue.
If the blower motor breaks down, the fan may continue running even if the thermostat is off or the furnace isn't producing warm air. The problem could be a blown fuse, corroded wires, or other issues with mechanical components, all of which require professional furnace repair.
Most furnaces will turn on and run for several minutes before reaching the desired temperature and shutting back down. This can happen anywhere from three to eight times an hour, depending on the condition of the furnace and the outdoor temperatures.
No, the coolant temperature sensor cannot be reset.
The engine coolant temperature sensor, or ECT is just a resistor affected by temperature—nothing's being stored on it and it has no software. The ECT works by receiving a signal from a computer called the engine control unit, or ECU.
One of the most common issues is the thermostat. The wiring, switches, or heating sensors can fail on your unit. If this is the case, then you'll need to replace the thermostat with a newer model. A damaged primary controller can also cause the furnace to stay turned on.
If your heater won't turn off, the first thing you do is check the thermostat. The thermostat controls how the heating system runs. It detects the indoor temperature and signals the furnace to start or stop. So, if the thermostat malfunctions, it can signal the unit to run continuously.
"Your system's [furnaces] aren't designed to run in temperatures that are below-zero for long periods of times," Marchand said. To help alleviate some of the stress off of systems during these cold temperatures, set your thermostat a few degrees lower than what you're used to.
Check the thermostat.
There may be a wiring problem or worn batteries. If changing the batteries doesn't work, you will likely need a new thermostat. Contact your service technician to set that up.
One reason why your furnace blower won't turn off is because of incorrect thermostat settings. For instance, the blower will continue blowing if the settings are higher than what your furnace can achieve. This is because it will continuously heat the space in an attempt to reach the set temperature.