Why Is My Furnace Not Blowing Hot Air?

Your furnace is running everything seems fine, but then you begin to notice that the air is not warm at all, in fact, it is downright cold. Why is this happening? Should you be alarmed?

The simple answer is: We can’t be sure

But what we can do is share our knowledge about this problem, some repairs can be done yourself, but other scenarios need to be inspected and repaired by a professional. One Hour Heating & Air Conditioning® of the Bay Area will help you if the job is too technical.

Check The Thermostat Setting

Is your furnace blowing cold air and you are noticing the fan is always on?

Checking the thermostat is where any technician will begin when trying to diagnose the problem. If your thermostat’s fan setting is set to ON, then your furnace blower will constantly be operating ever when it is not putting warm air into your home. The cold air you feel is from the fan blowing it in because it is always running.

To fix this issue is simple, just flip the fan switch from “ON” to “AUTO.” Auto setting will tell the furnace only to blow warm into your home when the furnace is on.

Furnace is Overheating

Furnace overheating can be the cause of your cold air dilemma. Changing the dirty air filter can solve this problem. The dirty air filter blocks the airflow, causing the furnace to run longer to heat your home until it overheats.

It is important to note that constant overheating can damage your heat exchanger. When the problem reaches the heat exchanger, then it is time for a replacement. Do not wait for this to happen, replacements are more expensive than repairs.

Pilot Light is Out

  • Relight the pilot light if you notice it is out. The instructions on how to do this are usually located on the furnace itself. If not, try to find the manual that came with the furnace.
  • Check to see if the furnace’s gas valve switch is on
  • Clean the pilot light
  • Replace the thermocouple

This problem can be complicated if you have never handled equipment before. You can replace the thermocouple yourself by buying a replacement at any home improvement store. But, if you are not familiar with how to remove and replace your current one, feel free to call a technician from Bigham’s One Hour Heating and Air Conditioning.

Dirty Flame Sensor

If the flame sensor is dirty the gas burner won’t stay lit. This will cause your furnace to cycle on and off.

Not Enough Gas

The gas supply to your furnace could have been cut off. The result is that your furnace will not have the gas needed to supply the warm air your asking of it. The furnace will even lock down in this instance for safety measures

Clogged Condensate Drain Lines

This applies to the newer and higher efficiency furnaces. If the drain lines are clogged it can prevent the burner from lighting.

Damaged Ducts

Your warm air goes through the ducts, but if your ventilation has holes in them they will let cold air come in contact with the air being blown into your home.

Wrong Sized Furnace

Size does matter in this situation. If your furnace is improperly fitted for your home then that can be the cause of your cold air. Furnaces too small cannot effectively heat your whole home. Furnaces too big will cycle on and off. Lack of power or a confusion in the mechanics is your problem here.

The cold air blowing in your home is not good and the problems can vary. If your furnace is the wrong size then you will need to get a new furnace. An HVAC technician can help you with the sizing.

Call One Hour Heating & Air Conditioning® of the Bay Area for furnace repairs for the cities of Santa Rosa and surrounding Sonoma County.