Leak in your ductwork is preventing adequate
If your thermostat isn't set correctly, it can cause your HVAC system to blow cold air even in the winter. If your furnace filter is clogged, it can restrict airflow, causing the furnace to overheat and shut down the heating element. The blower stays on to cool down the furnace, leading to cold air circulating.
If your air conditioner won't blow hot air, there is a possibility that it is having trouble receiving power. It could be a bad breaker, faulty wiring, or an undersized breaker. You can start troubleshooting by looking for signs like corroding or fraying wires, burnt breakers, and more.
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.
Start with the batteries. It may seem obvious, but one of the most common problems homeowners report is the thermostat's lack of power, which is often a matter of dead batteries! If your thermostat won't turn on the heat in your home, change out the batteries and see if that fixes the problem.
Thermostat is malfunctioning. Air filters are dirty and clogged. Furnace's blower motor needs repair. Pilot light is malfunctioning (on a gas furnace)
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.
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.
If these steps don't resolve the problem, it's essential to call a licensed HVAC technician for professional diagnosis and repair to ensure the heating system is restored promptly and safely.
While furnaces can stop operating for complicated reasons, home owners should check a few usual suspects first behind a lack of hot blowing air: Electrical problems causing a loss of power. Blocked air vents and ducts restricting airflow. Improperly configured thermostat settings.
Often, no heat in the home is a result of thermostat issues, whether they be true malfunctions or errors in settings. Whenever you notice no heat, check your thermostat first for troubleshooting. Make sure your thermostat is on – the display should be on as normal. If it's not, there could be a power issue.
If your furnace's problems continue, contact an HVAC expert. Also, if you notice discoloration when you check the pilot light, get professional help. If there are cold spots in your home, even though hot air is coming out of the air vents, the issue could be different from your furnace not working.
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 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.
If you're asking “Should the fan be on when the heat is on?”, think about your priorities. Keeping the fan on auto is fine if you prioritize energy efficiency. If comfort and air quality are at the top of your list, keep the fan on.
The electrical wiring within the boiler may have come loose, the programming within the boiler may have malfunctioned, the cylinder thermostat may need replacing, the fan may have stopped working, the pump may have broken… The list of potential problems is almost endless.
Switch the boiler off and on again
You should find the power switch close to the boiler or in an airing cupboard. Switch it off for a few seconds and then turn it back on again to see if this kickstarts your heating.
Your thermostat will not be able to reach your desired temperature if you have something blocking the vents. Check the vents around your home and make sure you do not have any items such as furniture in the way of your vent's airflow. While you're at it, make sure all of your vents are open.
When you turn the furnace on but no heat comes out, there may be an obstruction. Dirty air filters restrict airflow, which can make it feel like not much heated air is coming out of your vents. Check the furnace filter and replace it if its surface is covered with contaminants.