Sometimes a gas furnace blows cold air because of faulty parts.
You can fix some of these issues without the help of an HVAC contractor.
But first, you have to know how to troubleshoot and repair a broken HVAC system. The simplest way to figure out a problem with your HVAC equipment is by opening the heat registers. Often, the heat registers get closed accidentally. If too many are closed simultaneously, it could result in heat build-up in the furnace, prompting it to shut down automatically. Check your thermostat and its settings. The thermostat’s settings should be on heat and the fan on auto. You should set the temperature at about 10 degrees above your current home temperature to trigger your furnace to emit heat. Check its fuses, circuit breakers, and batteries to ensure that it’s getting power. You also need to clean your thermostat’s interior components to remove debris and dirt that could be inhibiting the HVAC system’s proper functioning. Proceed to check the furnace power and reset your furnace. Inspect the furnace electrical switch to be sure that it’s in the ON position, and then press your furnace’s reset button just in case it was automatically shut-off when the furnace got too hot or experienced other malfunctions. The other reason why your furnace is not heating could be clogged air filters. A dirty furnace filter inhibits proper airflow through your furnace, causing it to overheat and ultimately shut down automatically. Older gas furnaces with standing pilots have more issues with pilot light than new HVAC units. The furnace will not turn on or heat up if the pilot light won’t turn on. Finally, check your HVAC equipment’s flame sensor, whose role is to safeguard the furnace by ensuring the gas flows when there’s a flame to ignite only. If the flame sensor is damaged, it may stop your gas furnace from heating up.