If your furnace fan won't turn off, you most likely have one of these 3 problems: Your
furnace fan limit switch is set to “manual override
” The fan limit switch is faulty and needs to be replaced. There's a problem in your thermostat wiring.
Is it OK to run furnace fan constantly?
Running your furnace fan all the time isn't exactly a bad thing. In fact, there's no need to worry about the fan wearing out or breaking down because
it's designed to run continuously
, and there's an array of benefits connected to this. Here are some of them: Better circulation of heated and cooled air.
Why is my fan running when my thermostat is off?
Over time, relay switches can become stuck or damaged, preventing the thermostat from communicating with the fan. Essentially, this means that
the fan isn't receiving the commands you're relaying to the thermostat
. So even if you turn your AC off, the fan will continue to run.
Why is my furnace running constantly?
Some other problems that may cause a furnace to run constantly include a clogged furnace blower or a furnace blower/motor that needs
lubrication
—both of these issues will force your furnace to work ineffectively. Also, be sure to check that the fan switch on your thermostat is set to AUTO, not ON.
Why is my fan not turning off?
The most common reason that your Air Conditioner fan won't turn off is
because a stuck relay keeping the circuit closed
. … Double-check the thermostat and make sure the fan is not set to ON, and that it still runs when switching it to AUTO or OFF (if your thermostat has an OFF setting).
Is it better to have furnace fan on auto or on?
Keeping your fan
on AUTO
is the most energy-efficient option. The fan only runs when the system is on and not continuously. There is better dehumidification in your home during the summer months. When your fan is set to AUTO, moisture from cold cooling coils can drip and be drained outside.
How much does it cost to run furnace fan all the time?
The average kWh in the US costs about $0.12 so it costs about $43 per month, or
about $520 per year
, to run a fan continuously.
How do I know if my fan limit switch is bad?
The most common sign of a malfunctioning limit switch is
the continuous operation of your furnace's blower
. Just as the limit switch won't allow the fan to turn on until the warm air has reached the right temperature, the limit switch also shuts down when the air cools to a certain temperature.
Why does my heater keep running after it has reached the set temperature?
When your furnace keeps running after the temperature has been reached:
Check the blower motor
– Your forced air heating system uses a blower to push air through ducts and into your living space; sometimes, the blower runs at the same time that your furnace is heating the air, but sometimes it runs on its own.
How do you know a thermostat is bad?
- Your HVAC Keeps Turning On or Off. …
- Faulty Thermostat Readings. …
- Suspiciously High Energy Bills. …
- Constant Temperature Shifts. …
- Thermostat Is Too Old. …
- Thermostat Fails to Respond to Changed Settings. …
- Your HVAC System Short Cycles.
How long can a furnace run continuously?
If your furnace is operating correctly, it should cycle about 2 to 3 times per hour. How long it operates depends on how cold it is outside. In milder temperatures, it may run for
10 to 15 minutes
. The colder it gets, the longer the run cycle will be.
Why does my furnace run but not heat?
Furnace filters
Dirty filters are the most common cause of furnace problems. Dust and dirt restrict airflow—and if the filter gets too clogged, the heat exchanger will overheat and shut off too quickly, and your house won't warm up. If the blower is running but no heat is coming out,
replace the filter
.
How long should a furnace run before shutting off?
With all that being said, if there are no extreme factors involved, the average run time for a furnace is
10-15 minutes per cycle
. Your furnace may need to run two to three times an hour to maintain your desired temperature if your home has average insulation.
How long should fan run after AC turns off?
Your HVAC fan should turn on and off with the rest of your heating and cooling system. It's normal for the fan to kick on a couple of minutes before heating starts or to stay on for a couple of minutes after cooling stops, but your
fan shouldn't run for hours on its own
.
Should the fan be on when the AC is off?
Constantly turning the fan on and off can cause wear and tear to your system, which can reduce its lifespan. … To avoid this, it may be
best to leave the fan on
. Running your heating and cooling fan even when the AC isn't on helps circulate air throughout your home for consistent comfort.
Why AC fan stops working after a while?
One of the most common reasons fans stop spinning is
because of a dead capacitor
. … Each air conditioning system has several capacitors, including the start capacitor, which sends signals to the motor, and the run capacitor, which keeps the motor running. Capacitors can go bad over time and need to be replaced.
