We often get the call that peoples furnaces are blowing cold air instead of the warm air they expect. There are a few things that can be causing this issue. Here are a few things to look at to see if your issue is a simple fix. The first thing to check is your filter. If the filter is dirty and clogged it restricts air flow and makes the furnace stop working the right way. Your furnace can overheat which will cause unnecessary breakdown. This is a simple fix because you just change the filter and that could solve your problem. You are supposed to be changing the filter every month to prevent air flow restrictions and prevent excess dirt and dust getting into your HVAC system. Your pilot light may have went out which causes cold air to blow out instead of warm. Go take a look at your furnace and see if you can see the flame. If your gas has been shut off you will not have warm air. I know it seems like common sense but gas issues you are not aware of will cause cold air to blow out of your furnace. If your thermostat fan is set to ON, it will blow cold air at times because it will be running constantly. The best position is AUTO so it starts and stops as needed. Another issue you may have is a high limit switch being faulty. The high limit switch can trick the board into thinking the furnace is over heating and make it blow out cold air. If you have an issue with your hot water tank it could also cause the furnace to blow cold air. As you can see there are multiple causes of the furnace blowing cold air. If you check and change the filter and that has not fixed the issue then you need to call a qualified tech at Bartlett Heating and Air to come out and fix your furnace today!