7 Reasons Why Your HVAC is Not Blowing Warm Air and What to Do Next (2024)

The last thing you want to do is wake up or come home and discover your heater is not working properly. Brrr. This can be uncomfortable and risky to everyone living in the home, even your pets.

As soon as you notice your heater isn’t working, get on the phone with your favorite HVAC company. Do not wait until the cold becomes unbearable. Pull out space heaters or start a fire in your fireplace, but do not heat your home with your oven. This could cause a dangerous build-up of carbon monoxide gas. Instead, we recommend contacting a licensed HVAC professional for assistance to keep your HVAC unit operating at peak efficiency.

Several reasons can cause your HVAC unit to stop the circulation of warm air. Some are easy and you can check them yourself, while others require the help of an expert.

Here are some things to look for with your HVAC unit is not blowing warm air and how to get it working again.

How Does a Furnace or Heater Work?

To better understand what may cause your heater to malfunction, it will help to know how it works.

Most heaters in our area are gas-fired furnaces. This means they burn natural gas or propane to create heat that is distributed around the home. Furnaces are equipped with many safety features to watch for high temperatures and combustion gasses so they are properly vented.

Heat pumps matched with an electric air handler are another efficient way to heat your home. Depending on the equipment specs, if the temperature is below 35-45 degrees F, the electric air handler can supplement the heat. Because we have a mild climate here on the Texas Gulf Coast, a heat pump can be an efficient solution to keep your home warm.

In general, heat pumps are an air conditioner that operates in reverse in the wintertime. The expansion valve makes this possible – it uses refrigerant to collect the warm air from the outdoors and bring it indoors while depositing cool air outside. They also have auxiliary heat strips in the electric air handler to warm the air before distributing it around your home.

Many things can cause a heater to break down. Let’s take a look at the top 7.

1. The Air Filter Is Clogged

A common problem with HVAC units including furnaces and heat pumps is air filters that are dirty and clogged. Ideally, they are replaced quarterly because it doesn’t take long for a filter to trap dust, pollen, hair, and more. Your air filters are located in the return air vents or they can also be located inside your ductwork or your furnace. If you’re unsure, a trusted HVAC technician can help.

If you have clogged filters, it prevents your HVAC unit from its ability to breathe and circulate the air. It can cause a furnace or heat pump to overheat, which will cause a safety measure to shut it down. That means warm air will stop circulating in your home.

Replacing dirty filters is a quick and easy way to reduce wear and tear on your HVAC system and it can fix a heater that isn’t working.

2. Furnace Is Turned Off

If you have been in the attic or closet putting away holiday decorations or another professional has worked in it, make sure you check that the power switch on your furnace is in the “on” position. Many times it is easy for this power switch to be turned off by mistake.

If this is the case, a flip of the switch can make a world of difference and get your heater working again. It can also save you a service call.

3. Heat Pump Has Leaking or Low Refrigerant

If you have a heat pump and it is low on refrigerant, your heat pump will not be able to adequately heat your home. This may be counterintuitive, but remember, heat pumps use refrigerant to move cool air out of the home in the cool season. Instead, they circulate warm air into the home.

If your heat pump is not blowing warm air, the refrigerant may be the problem. The unit could be running low and need additional refrigerant added. Needless to say, this isn’t something you can do on your own.

A refrigerant leak can cause this problem. It can also make the humidity in the home rise, making it feel cooler than it should. If you suspect a refrigerant leak, contact an HVAC professional right away.

4. There Is a Problem With Your Electrical System

Check your electrical breaker box to see if any fuses have tripped. If there is an issue related to electricity, it’s definitely a good idea to have a licensed professional HVAC technician take a look at your heat pump or furnace.

A lot of times the issue is related to a safety measure on a gas-fired furnace that is not working correctly. If this is the case, your furnace’s safety measure will prevent your furnace from operating by cutting the power.

In a heat pump, the auxiliary heat strips might be malfunctioning, which can also cause it to be too cold in your home.

More rarely there is an electrical issue that will require an electrician’s attention. In either case, an HVAC expert can troubleshoot your system and advise you of next steps.

5. Your Registers Are Blocked

Blocked registers or vents can also cause a heater breakdown in the same way that clogged air filters do. If your HVAC system can’t take in enough air, it will be unable to distribute warm air.

It is also worth noting that occasionally a vent will get closed by accident. If just one room is colder than the rest, check to make sure the supply vent is fully open.

When something is obstructing the vent itself, only the room with that vent may feel cooler than other rooms in your home. That situation is an indication there may be a ventilation issue.

6. Ductwork Leaks and Inadequate Insulation Let the Heat Escape

A leak in the ductwork and inadequate insulation can also lead to temperature problems during the winter. If the ventilation system is compromised, warm air doesn’t get distributed around the home properly.

Sometimes rodents can move into your attic and create leaks, which can cause these problems.

A lack of insulation in an attic or the walls can also cause rooms to feel colder than they should. In this situation, your heater will work harder to maintain a warm room.

7. Heater Not Blowing Warm Air Because of Thermostat Settings

Make sure you check the thermostat which controls your HVAC system. The HVAC system will not turn on until the air temperature in the room rises above the setting you select.

The first step is to make sure the thermostat setting has not been changed.Make sure it is set to auto or heat. Occasionally, a thermostat will be set to cool instead of heat, which causes the problem. Once you switch the thermostat to heat or auto, your heater should start right up.

If your thermostat takes batteries, check and replace them if necessary. If your thermostat is set correctly and your heater is still not coming on, you may have a faulty thermostat. If these fixes do not work, a call to an HVAC professional is in order.

Proper Maintenance

As with any machine, your central air conditioning and heating unit or heat pump needsregular maintenance. Filters need to be changed and all other working components need to be examined by a professional.

The standard recommendation is to have a maintenance tune-up twice a year. This should happen in the spring and the fall for your central air conditioner and heater or heat pump. The technician can check your HVAC system and make any tweaks or repairs necessary before the weather gets cold.

This not only keeps your unit running efficiently, but also helps reduce the risk of unexpected breakdowns and more expensive problems in the future.

There will eventually come a time when your HVAC unit is costing more and more to repair. When that happens, it may be time to considerreplacing your system.

Banish the Chill

With Houston’s mild winters, now is definitely the time for your furnace or heat pump to be running well. If you have the problem of your heater not blowing warm air, it will not take long for the inside of your home to be miserably cold.

Many reasons can cause this problem ranging from being very easy for a homeowner to fix to requiring expert help. If you are not completely sure what the problem is, it is smart to have an HVAC professional come and assess the situation for your safety and your own peace of mind.

Contact Rob and Kenny at Terry’s A/C & Heating at (281) 495-7830 for an expert repair in the Richmond, Katy, Fulshear, Texas area. We are a Carrier Factory Authorized Dealer and service all makes and models of air conditioning and heating equipment for residential and light commercial applications. For more information on how we can help get the warm air moving again in your home or business, pleasereach out to us. We would love to earn your business.

Photo credit: Canva.com/RossHelen

As a seasoned HVAC (Heating, Ventilation, and Air Conditioning) professional with extensive experience in the field, I've encountered and successfully addressed a wide range of heating issues. My expertise spans the technical intricacies of gas-fired furnaces, heat pumps, and various HVAC systems commonly used in different climates.

In the provided article, the author touches upon crucial aspects of HVAC systems, particularly focusing on the potential problems that may lead to a heater malfunction. Let's delve into the concepts mentioned in the article:

  1. Gas-Fired Furnaces and Heat Pumps:

    • Gas-fired furnaces are highlighted as common heating systems, burning natural gas or propane to generate heat distributed throughout the home.
    • Heat pumps, paired with an electric air handler, are also discussed as an efficient heating solution, especially in milder climates like the Texas Gulf Coast.
  2. How Furnaces and Heaters Work:

    • The article provides a brief overview of how heaters function, emphasizing safety features in furnaces and the operation of heat pumps in reverse during winter.
  3. Common Reasons for Heater Malfunction:

    • Clogged Air Filter: The importance of regularly replacing clogged air filters is emphasized, as they can lead to overheating and system shutdown.
    • Furnace Power Switch: Checking the power switch's position in the furnace is recommended, as it may be inadvertently turned off during activities like putting away holiday decorations.
    • Refrigerant Issues in Heat Pumps: Low refrigerant levels or leaks in heat pumps can hinder their ability to heat the home adequately.
    • Electrical System Problems: Issues with the electrical system, including tripped fuses or malfunctioning safety measures, can impact the functioning of both gas-fired furnaces and heat pumps.
    • Blocked Registers: Similar to clogged filters, blocked vents or registers can impede the airflow and result in a lack of warm air circulation.
    • Ductwork Leaks and Insulation: Leaks in ductwork and inadequate insulation are identified as potential causes of temperature problems, making the system work harder to maintain warmth.
    • Thermostat Settings: Incorrect thermostat settings, such as being set to cool instead of heat, can prevent the HVAC system from operating as intended.
  4. Proactive Maintenance:

    • The importance of regular maintenance, including filter replacement and professional tune-ups twice a year, is stressed to ensure efficient HVAC system operation and prevent unexpected breakdowns.
  5. Consideration of HVAC Replacement:

    • The article suggests that there may come a time when repairing an HVAC unit becomes costly, and replacing the system might be a more practical option.
  6. Expert Assistance:

    • Throughout the article, the recommendation is made to seek the expertise of licensed HVAC professionals for troubleshooting and resolving complex issues, emphasizing safety and system efficiency.

In conclusion, the provided article offers a comprehensive guide for homeowners facing heating issues, encouraging a mix of DIY checks and the involvement of HVAC experts to ensure optimal system performance and safety. If you have any specific questions or need further clarification on HVAC-related topics, feel free to ask.

7 Reasons Why Your HVAC is Not Blowing Warm Air and What to Do Next (2024)


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