Your furnace may be blowing air when turned off due to a malfunction in the thermostat, a problem with the fan setting, or issues with the furnace's control board. It is recommended to contact a professional HVAC technician to diagnose and fix the issue.
You need to call a qualified heating contractor for service.
Your furnace may be blowing cold air and not shutting off due to issues with the thermostat, a malfunctioning heating element, or a problem with the blower motor. It is recommended to contact a professional HVAC technician to diagnose and fix the issue.
Your furnace may be turning on and off and blowing cold air due to a clogged air filter, a malfunctioning thermostat, or issues with the ignition system. It is recommended to check and replace the air filter, ensure the thermostat is set correctly, and have a professional inspect and repair any potential issues with the ignition system.
The furnace fan switch controls the fan that circulates air in the heating system. When the switch is turned on, the fan starts blowing air through the ducts to distribute heat throughout the home. If the switch is off, the fan will not operate, which can affect the efficiency of the heating system by not distributing heat evenly.
Perhaps the pilot light is out and the gas has been turned off at the valve.
If it's blowing intake-temperature air, either you've got the fan alone switched on or the heating part isn't working for some reason. If it's a gas furnace, the pilot light may have gone out, or the gas may be shut off somewhere (at the furnace itself, at the emergency shutoff for the house, or possibly at the main inlet). If it's blowing actually COLD air (colder than intake), then you've probably got central air and you've somehow managed to turn on the air conditioner.
that usually means that you turned off the A/C on a higher degree. If it was cold in the morning and you had the A/C on 90 degrees, then turned it off, even when the A/C is off it will still blow out hot air. Vise Versa. If you had it at 65 degrees, turned it off, the air will still blow in cold.
If your thermostat is turned off but your HVAC system is still blowing air, it could be due to a malfunction in the system's wiring or controls. This can cause the fan to continue running even when the thermostat is set to off. It's recommended to have a professional HVAC technician inspect and repair the issue to ensure proper functioning of your system.
That is the function of the fan/limit control on your furnace. When the thermostat nears the point where the room temp setpoint is satified it shuts off the flame. The fan/limit control keeps the fan on for a minute or so to cool the furnace down before shutting off. Conversly, if your watch your furnace at start up you will see the flame lights first but the fan does not come on for a minute or so to allow the furnace to get hot and avoid blowing cold air into the home.
Here are some things to check. Is the thermostat turned up? Sounds silly but I went into many homes it was turned down, or the switch on the thermostat was turned to off Is the pilot lit? This assumes you have a standing pilot furnace. If it is spark ignition, does the park cycle start. Check all fuses and breakers
Probably the flame sensor.
It could be that the fan switch on the thermostat is turned on so the fan runs all the time not just when the A/C or heat is on. This is supposed to be the most efficient method.