- The first place to look is the thermostat. It may sound simple, but check to see that it is turned on. All modern thermostats have an on/off switch, but they are not clearly labeled with an “on” position. The “on” position is labeled “heat” or “cool.” Obviously you want to make sure the switch is in the “heat” position. If you have a programmable thermostat, be sure you bypass the program by adjusting the temperature number and pressing the “hold” button. If the heater still does not come on you’ll want to check to see if your thermostat has a replaceable battery and check it.
- Is your furnace running but not producing much or any heat? If so, skip to #5. If your furnace is still not on or does not fire up, look for an on/off switch at the furnace itself. It looks just like a light switch and is often attached to the unit itself, or very nearby. Make sure the switch is on. If you have central air-conditioning as part of your system and it worked properly over the summer, then more than likely your switch is already on (If no visible “on/off” markings on switch, try moving switch to opposite position and wait 10 seconds).
- If your switch is on and the furnace has still yet to run, check the breakers in your electric panel. The breaker could have tripped and the solution to the problem could be as easy as flipping the switch. A tripped breaker could be a sign of a larger problem that may require a technician to investigate.
- If all switches are on, the problem could be with the cover on the front of the furnace. The cover often has a trip switch which shuts off the system when it is opened. If the cover is not properly closed, the switch can prevent the furnace from running.
- If the furnace comes on and you don’t feel any hot air it could be that the furnace is not getting any fuel, or the pilot light is not lit. Check the fuel line and be sure that the valve is turned on. You can tell if the fuel valve is on if the handle runs parallel with the fuel line. If the handle is perpendicular to the line it is in the off position. If at this point you don’t feel any heat you may want to be sure you have paid the gas bill, or have oil in your tank.
- Next, be sure to check your filter even if it has been replaced recently. Check that you have the correct filter that is recommended by the manufacturer of your furnace. Some modern filters can be too restrictive for some furnace models. A whistling noise around the furnace while furnace fan is running may indicate a filter that is clogged or too restrictive.
- During winter months, the intake vent (round plastic pipe outside the house – the one pointing down) can become clogged with ice and snow. Check and clear any obstructions (ice and snow) from INSIDE the vent.