How do you fix heat blowing cold air?

If your home's heating system is blowing cold air instead of warm, it can be a frustrating and uncomfortable problem. However, there are several common causes and potential solutions to get your heat back up and running properly.

Possible Reasons for Heat Blowing Cold Air

There are a few key reasons why your heating system may be blowing cold air:

• Thermostat issue: The thermostat may not be set correctly or could be malfunctioning, preventing the system from properly triggering the heating cycle.


• Clogged air filter: A dirty or clogged air filter can restrict airflow and prevent the system from heating the air effectively.


• Refrigerant leak: If your system uses a refrigerant-based heat pump, a refrigerant leak can cause the system to blow cold air.


• Faulty heating element: The heating element or coil in an electric furnace or heat pump could be damaged or not functioning properly.


• Pilot light or ignition issue: In a gas-powered furnace, a problem with the pilot light or ignition system can prevent the burners from lighting and heating the air.

Identifying the root cause is the first step in resolving the issue and getting your heating system back to blowing warm air.

Steps to Fix Heat Blowing Cold Air

Here are some steps you can take to troubleshoot and fix the problem of heat blowing cold air:

1. Check the thermostat: Ensure the thermostat is set to "heat" mode and the temperature is set higher than the current room temperature. Replace the thermostat batteries if needed.


2. Replace the air filter: Change the air filter if it is dirty or clogged, as this can restrict airflow and prevent proper heating.


3. Inspect the heating element: If you have an electric furnace or heat pump, check the heating element for any signs of damage or malfunction.


4. Check the pilot light or ignition: For gas-powered furnaces, ensure the pilot light is lit or the ignition system is working correctly.


5. Inspect for refrigerant leaks: If you have a heat pump, have a professional technician check for any refrigerant leaks that could be causing the system to blow cold air.


6. Schedule professional maintenance: If you've tried the above steps and the problem persists, it's best to have a qualified HVAC technician inspect and service your heating system.

By following these troubleshooting steps, you can often identify and resolve the issue causing your heating system to blow cold air, restoring warmth and comfort to your home.

Should I turn my heat off if it's blowing cold air?

No, you should not immediately turn off the furnace. First, check your thermostat to ensure it's set to "Heat" and the desired temperature is higher than the current room temperature. If that's not the issue, try turning the furnace off, waiting a minute, and then turning it back on to reset it. If the problem persists, it could be due to a clogged air filter, a dirty flame sensor, or an overheating issue, and you should contact a professional. 
This video demonstrates how to check your thermostat and clean your furnace's flame sensor: 1mEveryday Home RepairsYouTube · Dec 8, 2022
First steps to take

• Check the thermostat: Make sure the thermostat is set to the "Heat" mode and the set temperature is higher than the current room temperature. 
• Reset the furnace: Turn the furnace off at the thermostat, wait for about a minute, and then turn it back on. This can sometimes resolve the issue. 

What to do if the problem continues

• Inspect the air filter: A dirty or clogged air filter can restrict airflow, causing the furnace to overheat and shut down the heating cycle. Replace it if it's dirty. 
• Check the flame sensor: A dirty flame sensor can be a common cause of the furnace shutting off prematurely. If you are comfortable doing so, you can clean it gently. 
• Look for other signs: Check the furnace for any flashing lights, which can indicate a specific error code. Refer to your furnace's manual to interpret the code. 

This video explains three common reasons why your furnace might be blowing cold air: 59sDIY with Michael BordersYouTube · Feb 20, 2020
When to call a professional

• If the simple reset doesn't work or you're not comfortable with the other steps, it's time to call a professional HVAC technician. 
• A technician can diagnose more complex issues, such as a faulty limit switch, a problem with the gas supply, or damaged ductwork. 

Why is my furnace running but only cold air?

A furnace blowing cold air could be due to several reasons, including a temporary hold-up in heating (common at the start of a cycle), issues with the gas supply, a malfunctioning pilot light in gas furnaces, or problems with the thermostat setting.

Why is cold air blowing when the heat is on?

Cold air can blow when the heat is on due to a dirty air filter, thermostat issues, or a problem with the furnace's ignition or gas supply. For heat pumps, it could be a normal defrost cycle, while other issues include a clogged condensate line, a cracked heat exchanger, or a malfunctioning blower motor. 
Common causes

• Dirty air filter: A clogged filter can restrict airflow, causing the furnace to overheat and the safety limit switch to turn off the burners, leading to cold air blowing from the vents. 
• Thermostat settings: The thermostat's fan might be set to "on" instead of "auto." In this case, the fan will run continuously, blowing unheated air between heating cycles. It could also have dead batteries. 
• Ignition or pilot light issues: If the pilot light has gone out or the igniter is faulty, the gas won't ignite, and the system will blow cold air. A dirty flame sensor can also cause the furnace to shut down. 
• Heat pump in defrost mode: If you have a heat pump, it may temporarily blow cold air when it goes into a "defrost cycle" to melt ice off the outdoor coils. It will switch back to heating after a few minutes. 
• Blocked condensate line: A clog in the condensate line can cause the furnace to shut off, leading to cold air. 
• Duct leaks: Leaky or poorly sealed ducts can lose hot air before it reaches your home or allow cold air from an unconditioned space to enter the system. 
• Overheating: The furnace may be overheating due to a lack of airflow (e.g., from a dirty filter or blocked vents), which triggers a safety limit switch to shut it down and blow cold air. 

What you can do

• Check the thermostat and make sure the fan is set to "auto" and the system is in "heat" mode. 
• Inspect and replace the air filter if it's dirty. 
• Check if there are any furniture or obstructions blocking the return air vents. 
• If the problem persists, you may need a professional to check for issues with the gas supply, pilot light, flame sensor, or heat exchanger. 

How do you fix your heater when it's blowing out cold air?

To fix a heater blowing cold air, check your thermostat settings to ensure it's on "Auto" and set to heat, then replace the dirty air filter. If that doesn't work, try resetting the system by turning it off at the breaker for five minutes, or check for a pilot light that needs relighting. If the problem persists, it could be a more serious issue like a dirty flame sensor or a malfunctioning part, which may require a professional. 
Step 1: Check thermostat settings and power 

• Set to "Heat" and "Auto": Make sure the thermostat is set to the "Heat" mode, not "Cool" or "Fan". Change the fan setting from "On" to "Auto" to prevent the fan from running when there's no heat. 
• Check the power supply: Verify that the circuit breaker for your furnace is on and that the furnace switch isn't turned off. 

Step 2: Replace the air filter 

• A dirty or clogged air filter can restrict airflow, causing the furnace to overheat and shut down the heating element while the fan continues to run, blowing cold air. 
• Locate and replace the filter. Ensure the new filter's arrow points in the correct direction for airflow, and tighten any access panels securely. 

Step 3: Perform a system reset or relight the pilot 

• System reset: Turn the power to the furnace off at the breaker box, wait for at least five minutes, and then turn it back on. 
• Relight the pilot light: If you have an older gas furnace, check if the pilot light is on. If it's out, follow the manufacturer's instructions to relight it. Safety first: turn off the gas supply before relighting and call the gas company if you smell gas. 

Step 4: Call a professional

• If the above steps don't solve the issue, the problem may be more complex. Contact a qualified HVAC technician to diagnose and fix problems like a dirty flame sensor, a faulty igniter, or a broken heat exchanger.