A clogged filter is one of the most common causes of a heater blowing cold air. However, even if you replace the air filter with a new one, dirt, and other particles can still be inside the system. This could lead to overheating in the long run.
If your furnace turns on but no heat is produced, there may be a problem with the fuel supply or the ignition system. If something is stopping your furnace from receiving gas, there is no fuel to combust so the furnace will not create any heat. The furnace turns on but no heat comes out.
Start by replacing the air filter. If this doesn't solve the issue, you may need to adjust the thermostat heat anticipator or troubleshoot the blower motor. The blower motor may need to be oiled at lubrication points, or have its belt adjusted (if it is too loose) or replaced (if it is frayed).
If your furnace is blowing cold air in your home, this is a sign of an issue with the flame detector, gas supply, air filter, pilot light, or condensate lines. Many of these issues are able to be easily solved on your own by sanitizing or replacing components in the gas furnace.
First, check to make sure the thermostat is set correctly. You will want to make sure that the fan control is set to auto, and not 'on'. If the thermostat appears set correctly, turn off your heater at the thermostat and check the filter. If the filter is dirty, replace it.
This problem often points to inadequate circulation of warm air. It could be due to blocked vents, a failing HVAC fan, or issues with the furnace itself. Ensure that furniture or drapes are not blocking your vents. Also, check if your furnace's filter is clean, as a dirty filter can restrict airflow.
If the heat is running and your house has oddly cold rooms, they are unevenly heated, or vents or radiators aren't giving off much heat – there could be a problem with heat delivery. Insulating your home will surely help keep the heat inside, but it first needs to be properly delivered.
If the furnace is running but blowing cold air, there can be a number of things that have gone wrong, from a change in thermostat settings and a filter that needs changing to a pilot light being out and sensors being dirty.
Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it. For those wondering specifically how to reset air conditioner thermostat models, the process is generally the same.
Radiators might not be getting hot due to trapped air requiring bleeding, a malfunctioning boiler or central heating pump, thermostatic radiator valves that might be stuck or set too low, or the central heating system having sludge or rust which causes blockages.
#1: Dirty Air Filters Block Proper Airflow
While it's a relatively simple task, it's one many homeowners put-off or simply forget to do. The truth is a dirty air filter is one of the top reasons furnaces don't work their best to warm-up a home quickly.
Possible reasons include thermostat issues (incorrect settings or dead batteries), power problems (tripped circuit breaker or blown fuse), and furnace malfunctions (dirty air filter, faulty ignition system, or tripped safety switches). Checking these areas can help identify the issue.
A furnace blowing cold air could be the result of a leak in your ducting. Over time, the changing temperatures wear on all sorts of things, including your ductwork. In fact, it's rather normal for ductwork to develop leaks over time. When ductwork has a leak, cold air will enter a duct and blow into your home.
Short cycling is a common sign of a bad flame sensor. The sensor thinks that there isn't a flame, so it shuts off the gas as a safety mechanism. Except, there is a flame and without the gas to supply it, it dies. This is a frustrating problem, but an HVAC technician can fix it.
This can occur if there's a malfunction in the furnace's components, such as a faulty limit switch or a blocked heat exchanger. In such cases, it's crucial to consult a professional HVAC technician for a thorough inspection and necessary repairs.
Sometimes, your furnace or AC system won't hit the thermostat temperature because the thermostat isn't correctly calibrated. This can be a common issue with new thermostats, and also often occurs after a power outage or when the thermostat's batteries are running low.
Check the Furnace Filter.
A dirty furnace filter is one of the most common reasons furnaces don't produce enough heat. Luckily, this is an easy and inexpensive fix. While you're at it, buy one or two extras and make a note in your calendar to check it again in a month.
If your home isn't warming up as expected, a dirty air filter, blocked vents, or thermostat issues might be to blame. Check and address these issues before considering professional assistance.
Make sure all vents and radiators are open and not blocked by furniture or curtains. Blocked vents can prevent the warm air from circulating freely in your rooms. It's also a good idea to bleed your radiators to remove any trapped air that can cause cold spots and reduce their efficiency.
For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.
Leave the breaker(s) off for at least 10 minutes while the system is off and “rebooting.” After 10 minutes have elapsed, go back to the breaker box and flip the HVAC breaker(s) back on.