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Why Is My Furnace Blowing Cold Air?

Person wearing a blanket over their shoulders With temperatures falling below zero several times already this winter season, now is not the time for your furnace to be blowing cold air. If this happens to you, there are several possible causes and solutions.

Heating systems are generally easy to maintain. However, no matter what type of furnace you have, there are a few things you can check to make sure it is functioning properly.

Check the heat/cold source, the distribution system, and the thermostat. Make sure, if your system is gas or oil, that the fuel is reaching the unit. Verify that your blower and distribution center are spreading heat throughout your home, and check that your thermostat is working properly.

If a fuse blows or a circuit trips repeatedly when the unit is on, this usually means there is an electrical problem. In this case, you should call in a professional before proceeding any further.

Here Are Some Common Causes of Why Is a Furnace May Be Blowing Cold Air.

  • You may have a dirty or clogged air filter restricting airflow. In this situation, change the air filter and see if your furnace starts blowing warm air. When airflow is restricted due to a dirty or clogged air filter, the furnace could overheat, and repeated overheating can damage the furnace’s heat exchanger. When a furnace overheats, you may only get cold air blowing out.
  • Check the settings on the thermostat. Is it set to ON? Is the furnace blowing cold air only sometimes or all the time? The thermostat’s fan setting should be set to AUTO.
  • Check the pilot light. When older gas furnaces blow cold air, it could be because the pilot light has gone out. Follow the manufacturer’s instructions to re-light the pilot light safely. You also may need to clean the pilot light in order to light it properly and allow gas to come through it.
  • The furnace’s flame sensor could be dirty. Pilotless ignition furnaces use a flame sensor. If the flame sensor is dirty, a furnace may turn on and begin to heal, but become cold quickly.
  • Other problems include an inadequate gas supply to the furnace, duct problems, condensate clogs, troubles with the circuit board, faulty igniters, or any number of more serious issues. All of these complications require calling in a professional.

Professionals recommend that your home’s heating and air conditioning be inspected once in the spring before temperatures rise and once in the fall before temperatures drop. Not only will inspection and a tune-up assure you that the unit is in good working condition, but it also can help prolong its lifespan and save energy. Without an inspection, your unit could stop working, suddenly leaving your family in the cold.

Inspections and service can reveal carbon monoxide leaks, energy leaks and other problems that may have occurred while not in use. Whether it’s gas or electric, not keeping your system maintained can cause it to run less efficiently and increase your monthly energy bills.

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