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Why Is My Furnace Blowing Cold Air?

A furnace is meant to keep the room warm, especially in winter. However, it is not uncommon to find out that a heater is running just fine, but it is blowing cold air. So what could be the problem? 

Several reasons could be causing this problem. Here some of the common reasons why a furnace is blowing cold air. Contact a trusted air conditioning service in the Inland Empire if any of the following is the reason for the furnace blowing cold.

Reasons Your Furnace is Blowing Cold Air

  1. Faulty Thermostat or Settings

A faulty thermostat could be the reason why the furnace is blowing cold air. Thermostats are gadgets that control the temperature of the furnace from zero to maximum. When this gadget is faulty, the temperature setting is zero. That’s why the system will be running just fine but no heating. A professional air conditioning service Inland Empire can help replace the faulty thermostat with a new one. The problem could also be the thermostat setting. So adjust temperature upward or turn on the AUTO mode.

  1. Clogged Air Filter

Most people don’t know that clogged or dirty air filters could be the reason why the furnace is blowing cold air. If the filters are clogged, there will be limited airflow into the vents hence causing the furnace to overheat. Consequently, overheating causes the safety control device or the limit switch to shut off furnace burners. So the fan will be running but no heat air from the burner. Hiring a professional AC Repair Inland Empire contractor will help replace air filters with new ones.

  1. Clogged Condensate Line

Some furnaces have a condensate line which helps to remove water collecting in it. This line should always be free of obstacles to ensure that water is not receiving in the furnace. If the line becomes clogged, it prevents that furnace from igniting. So if the heater is not heating, but it is running, check for clogs in the condensate line. 

  1. Inadequate Gas Supply

For those heating rooms with a gas furnace, an inadequate supply of gas can cause the system to blow cold air. If there is an insufficient gas supply, the system will go off for safety. So the burners will not heat, but the electric-powered fan will continue running. So if the gas supply is on, hire a professional gas service provider should fix the problem.

  1. Dirty Flame Sensor

For homes using pilotless ignition furnaces, the flame sensor could be the reason for the cold air blown into the room. The flame sensor keeps the furnace burning once it has started. But if the sensor is dirty, it will be unable to sense the flame. So the furnace will turn on, heat for a little while and turn off. The on and off-cycle will keep repeating itself since the gas burner cannot stay lit. Contact a professional air conditioning repair Inland Empire contractor to fix the problem.


If the above solution does not solve the problem, contacting a trusted air conditioning service in Inland Empire is the best option.

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