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Home » Blog » 5 Quick Fixes for a Furnace Not Blowing Hot Air

5 Quick Fixes for a Furnace Not Blowing Hot Air

One of the worst things that can happen on a cold winter day is discovering that your furnace isn’t blowing hot air. If this happened to you and you’re wondering, why, keep reading. I’ll walk you through a list of possibilities and provide you with our five quick fixes.

5 Reasons Why Your Furnace May Not Be Blowing Hot Air

So, let’s go over some of the reasons why your furnace has stopped blowing hot air. Some will be simple fixes that don’t pose a significant risk. Others will need the services of an HVAC professional.

1. Check That Your Furnace is Turned On.

I know what you’re thinking: “Well, duh. My furnace is, of course, turned on!” However, do yourself a favor and confirm that this is the case. Someone may have unintentionally turned off the power to your furnace.

Solution: Check to see if there’s a power switch on the furnace itself, and if not, look for one on a nearby wall

2. Clogged Filters

Dirty air filters are the root cause of many furnace and air conditioner problems. Filters should be replaced every three months in most cases, but this can vary depending on your household. 

If filters are not replaced or cleaned regularly, they will accumulate dust, debris, hair, pollen, pet dander, and other contaminants. This will eventually accumulate to the point where it obstructs airflow and may cause your furnace to overheat.

If your furnace overheats, one of the above safety measures will take effect and shut it down. Warm air will then cease to circulate throughout your home.

Solution: Examine your filters to see if they need to be replaced or cleaned. Maintain your filters regularly, as dirty filters are the source of many HVAC problems.

3. Electrical Issues

There are numerous possible causes for electrical problems with your furnace, making it difficult to pinpoint the source of the problem. However, here are a few things you can look into:

Loose wiring: Due to the constant vibration of your furnace, some internal wiring may become loose over time. If this occurs and it begins to short, your furnace may shut down.

Tripped Breaker or Blown Fuse: If your furnace isn’t working, check if you have a tripped breaker or a blown fuse.

4. Blocked Registers

Each HVAC system is built with a specific amount of airflow. If that airflow is obstructed in any way, the functions of your furnace will be disrupted.

Partially closing registers or supply vents is usually fine, but completely blocking them will eventually cause problems with your blower motor and stop moving hot air throughout your home.

Solution: Check that no supply or return vents are completely closed. This goes beyond simply closing the vents. You should also avoid blocking them with the furniture. Removing the grills and checking inside is also a good idea to ensure nothing is blocking them.

4. Failed Capacitor

Your HVAC system’s job is simple: it creates and distributes warm or cool air throughout your home. It’s your blower motor’s job to make this happen.

Once the blower motor is turned on, the capacitor’s job is to keep a steady supply of electricity flowing and your fan running smoothly.

If your capacitor has failed to function appropriately, the fan will not run as it should, and you will not have any hot air blowing throughout your home.

Solution: You can check a few things to see if you have a faulty capacitor.

Turn the thermostat and wait for your fan to start up within a few minutes. Alternatively, stay close to one of your registers to feel the forced air blowing out.

When the motor starts spinning, listen for a humming sound. When the motor starts, the speed gradually increases.

If you hear the hum, but the motor does not start, you have a restriction in the motor, which could be the capacitor.

If you determine that your capacitor needs to be replaced, you can contact Blue Sky Heating and Air LLC to replace it.


Fortunately, several causes of the furnace not blowing hot air are simple fixes.

To summarize:

  • Your furnace may not be turned on
  • Clogged filters
  • Electrical issues
  • Blocked registers
  • Failed capacitors

Check to see if any of these are the source of your issue. In most cases, if regular maintenance is performed, a lack of airflow will never be an issue.

However, if your furnace is still not blowing hot air, the best solution is to call HVAC professionals. If you’re in Austin, TX, or surrounding areas, schedule your service with Blue Sky Heating and Air LLC or text/call us at (512) 222-6666 for all your HVAC needs. Our professional HVAC technicians can diagnose and get the issue resolved fast. Book online with us https://blueskyheatingandairllc.com/online-booking/ and visit our facebookpage https://www.facebook.com/blueskyheatingandair.