heating system

Fixing Cold Furnace: Quick Solutions!

Experiencing a furnace that blows cold air when it’s freezing outside can be incredibly frustrating. Returning home after a long day of work, everyone anticipates warmth and comfort, not a malfunctioning heater. It’s like a double setback – you’re left feeling cold, and your utility meter keeps running, charging you for the furnace’s ineffective heating.

In such a situation, the best course of action is to contact a professional HVAC service for diagnosis and servicing. Calling a furnace heating repair company is the quickest and most reliable way to restore your heating system’s functionality.

While waiting for the licensed HVAC technician to arrive, it’s valuable to understand why your heater is blowing cold air and what steps can be taken to prevent this issue in the future.

How Furnaces Normally Work

To comprehend why a furnace might suddenly blow cold air, it’s essential to grasp its usual operation. Typically, the thermostat prompts the furnace to start functioning. When the thermostat senses that the indoor temperature has fallen below the homeowner’s desired setting, it activates the furnace to maintain a warm environment.

The thermostat sends a signal to the furnace’s control board, initiating the heating process. This process involves combustion, which heats up the heat exchanger. Simultaneously, flue gases are expelled through both the heat exchanger and the exhaust pipe.

Once the gases are discharged, the furnace’s blower fan circulates air past the heat exchanger. The cold air absorbs the warmth and is then distributed through the home’s vents. Understanding this standard process makes it easier to identify potential reasons for a furnace blowing cold air.

Common Reasons for a Furnace Blowing Cold Air:

Ignition Failure: The most frequent cause of a furnace blowing cold air is an ignition failure. Without a flame, the furnace can’t generate heated air to warm the house. Ignition issues can be triggered by:

  • A malfunctioning thermostat that activates the blower but not the furnace’s burner.
  • A defective circuit control board, which may prompt the blower but not the burner.
  • Problems with the pilot light or electric furnace ignition in newer systems.
  • Fuel depletion or issues with the gas valve in gas furnaces.


Safety Features: Furnaces have safety mechanisms that activate in response to abnormal heating conditions or failures. If none of the above reasons apply, a safety feature might have been triggered due to overheating or other issues.

Overheating: Surprisingly, an overheating furnace may blow cold air as a safety measure. The main limit, a safety feature, turns off the furnace’s ignition when overheating is detected, causing cold air to be circulated.

Cracked Heat Exchanger: A cracked heat exchanger is a serious concern that can cause cold air to be blown. It can also pose a risk of carbon monoxide leaks.

Restricted Airflow: Any obstructions or restrictions in airflow, such as blocked supply or return vents, dirty filters, or incorrectly sized ductwork, can lead to cold air being blown by the furnace.

Troubleshooting Steps: Check the thermostat settings to ensure it’s set to heating mode and the fan mode is on auto, not continuous.

  • Inspect all vents and registers throughout your home to ensure they are not obstructed.
  • Examine and replace furnace filters if they are dirty or clogged.
  • If these checks do not resolve the issue, it’s advisable to contact a licensed HVAC professional for a thorough diagnosis and safe resolution.

Preventive Measures:

Regular maintenance is the best way to prevent a furnace from blowing cold air. Scheduled professional maintenance ensures the furnace operates efficiently and safely. During annual inspections, technicians clean heating components, tighten connections, and replace worn-out parts.

To stay warm and comfortable throughout the winter, it’s essential to establish a relationship with a reliable HVAC service provider. At Global Heating and Air Conditioning , we offer comprehensive furnace inspections, tune-ups, maintenance, and repair services, ensuring your heating system operates at its best. Schedule your HVAC inspection today through our online appointment system.

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