The cause is most likely the limit switch is getting so hot it is opening causing the fan to turn on to cool the limit switch. They often will open around 130-145 and yours may be a little weak.
Why does my blower motor keep running?
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.
Why is my AC blower 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. If it’s not the relay, your thermostat likely has a shorted cable or needs to be replaced.
Why does the blower run after the furnace cycles off?
When the fan cycles back on while the burner remains off we figure that the heat exchanger is still so hot that even without the burner being on, the air in the plenum heats back up after the fan cuts off, causing the switch to turn the fan back on.
How long should blower run after furnace shuts off?
In normal operation, your furnace blower fan should come on 1.5 to 3 minutes after your thermostat calls for heat and should turn off several minutes after the heating cycle ends. Your blower should run constantly until the heating cycle ends.
Should HVAC fan always run?
Should I Always Keep My Fan Running? It is usually a good idea to keep a modern HVAC or furnace fan on. However, if you have ductwork in your attic, the summer heat can make running the fan impractical. Temperatures well above 100℉ can end up in your main living space.
Why wont my AC turn off when it reaches the set temperature?
When your air conditioning system keeps running and never seems to shut off, the problem could be linked to a number of malfunctioning components – frozen evaporator coils, a clogged air filter, a bad electrical relay switch that needs to be replaced, the fan blowing constantly, dirty condenser coils, a bad thermostat,
Why does my furnace come on every 5 minutes?
Blocked Exhaust Vent
This is another cause of a furnace overheating and short cycling. Short cycle time: 1-5 minutes. This issue can be dangerous too, since deadly carbon monoxide is dispersed through the vent. If it is blocked, the gas won’t escape, and it can leak out of the furnace and into your home.
How do I know if my furnace is short cycling?
If your furnace turns on and off repeatedly for short bursts of time, not allowing the house to reach its proper temperature, it is short-cycling.
How often should HVAC fan run per hour?
about 2-3 cycles per hour
Most systems should run about 2-3 cycles per hour.
Why does furnace blower run constantly?
If that fan switch is set to MAN (manual) or ON, it will force the blower to run continuously. Follow the steps below to check the settings of your fan limit switch: Remove the panel from your furnace and locate your fan limit switch. Check the small white button on the switch.
Should HVAC fan be 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.
What temperature should AC be set at in winter?
Set your thermostat to 68 degrees Fahrenheit in the winter
According to ENERGY STAR, setting your thermostat to 68 degrees Fahrenheit (20 degrees Celsius) when you’re home is the ideal balance of comfort and energy efficiency.
Is it OK to leave furnace fan on all the time?
As previously mentioned, newer models of furnace systems include fans that are designed to run continuously. Assuming that your heating equipment was properly installed by a professional and has correctly-sized ductwork, letting the fan run continuously may actually help extend its service life.
How can I make my heat pump more efficient in the winter?
Set it and forget it in the winter.
Heat pumps operate most efficiently when holding a steady temperature. Turning a heat pump down when you’re away or asleep may actually use more energy than leaving it on. The reason is that it has to work harder to come back to the desired temperature than it does to maintain it.
Is 72 a good temperature for heat in the winter?
The lower the temperature is inside of the home, the slower the rate of thermal energy loss. To achieve optimal comfort, it is recommended for homeowners to set their thermostats between 68 to 72 degrees while there are people inside of the home.
How often should a heat pump cycle on and off?
2 to 3 cycles per hour
It completely depends on the unit’s cooling capacity, the room temperature and the humidity. On the average, a 10 to 20 minutes shut down should be appropriate enough depending on the factors mentioned. And it should be within 2 to 3 cycles per hour max. Your HVAC unit is not designed to be running all the time.
