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Why Is My Furnace Blowing Cold Air? Part Two

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As noted in “Why Is My Furnace Blowing Cold Air?” Part One, nearly half of American households use natural gas for heating, and as temperatures plummet, the use of the home furnace rises.

Furnaces, just like all appliances, require maintenance or issues may arise, such as the furnace blowing cold air instead of heated air. We touched on a few reasons this happens in part one along with how to troubleshoot the repair. But there are still a few other causes of a furnace blowing cold air we didn’t mention previously. 

Those reasons include:

Too Much Condensation

Furnaces are the best thing since sliced bread on cold days and nights. One might think a metal machine with a flame inside might be immune to the cold, but it isn’t. Just like humans, HVAC systems can freeze- and thaw. For example, ice can build up in the gas valves, block them, and reduce heating effectiveness. When it thaws, if there is overflowing or standing water near the furnace, it signifies too much condensation has occurred in the unit, which tends to happen when the furnace isn’t used much (like over the summer).

Example of condensation on cold air intake.
Example of condensation on cold air intake.

To eliminate the effects of condensation:

  • Turn off the main power source of the furnace.
  • Check the condensate drain and remove the water in it.
  • Clean all parts of the furnace with a soft cloth and warm water.
  • If there is visible ice buildup on the valves, get electric tape and wrap it around the valve, then keep it there until all the ice melts.
  • When done, put all furnace parts back in their rightful home and switch the power/gas on.

Presuming there are no other issues with the unit, the furnace should produce warm air. If the issue persists, contact us.

The Air Ducts Leak

Leaks from the air ducts signify a major issue. If this issue persists, the furnace may blow cold air whether it has enough gas to burn or not. Besides an over-abundance of cold air, other signs of leaking air ducts are:

  • an excessively dusty home.
  • rising utility bills.
  • uneven heating.
  • Visible holes in the ducts.

Solution: Unfortunately, this problem can’t be solved on your own.  An HVAC professional needs to inspect the condition of the air ducts and recommend an ideal solution. If the leaks are not extensive, then patches may resolve the issue. However, extensive and/or excessive leaks may require a duct replacement.


The Fan Is Faulty

If the air from your furnace comes out cold, then becomes warm, then becomes cold again, then the furnace has a faulty fan. The fan is usually located beneath the furnace hood and is meant to distribute heat evenly to all parts of the home. So, if some parts of your home are colder than others, then the fan may be at fault.

Solution: Contact a professional HVAC contractor to inspect the fan. If the fan is damaged beyond repair, then it may be wise to consider an HVAC system replacement.

The Furnace Is Overheating

When a furnace is overheating, it will blow hot air, then cold air, then shut off. This cycle may continue for an extended period, and still, your house remains cold. When the furnace overheats, the heat exchanger becomes abnormally hot. The fan limit switch detects this excess heat and turns off the unit. You can’t get warm air when the fan is off, and that’s why you experience cold air. Once the heat exchanger begins to cool, the fan limit switch tries to turn on again, and viola, more cold air.

Solution: Check the filters and confirm that they are not clogged. The clogs may block the filters, prevent the entrance of cold air into the furnace, and cause the overheating problem. Ensure that the air supply vents are opened well. Closed vents prevent warm air supply to your house and block cold air from getting in. Contact us if the problem persists.

Furnace Still Blowing Cold Air? Contact an HVAC Professional

Are you still getting cold air from your furnace? Check out Part One of “Why is My Furnace Blowing Cold Air?” for more ways to troubleshoot, or skip it and get help from Phoenix Air ATX

Most of these issues are not serious, and you can eliminate them if they’re caught and resolved early. So, don’t dump your furnace or suffer in silence. Contact Phoenix Air ATX take care of your furnace maintenance, repairs- and if needed- furnace replacement or installation.

Peace of Mind for $179 a year

Join our Maintenance Plan Program and get all the perks of membership: 10% discount on repairs, seasonal tune-ups, priority scheduling and more. 100% satisfaction guaranteed.