AC Blowing Warm Air: Common Reasons & How to Reset an Air Conditioner

why my ac blowing hot air


Jake Smith, Online Marketing Strategist
Technically Reviewed by Jake Smith, Online Marketing Strategist on Jul 12, 2023 | Written by Alpha Mechanical Editorial Contributors

With Summertime in full swing, it is every air conditioner’s time to shine. One of the worst feelings is turning down the air on your thermostat and your vents begin to blow warm air. When your air conditioner is blowing warm air especially in the Sacramento, California region, it is crucial to resolve the predicament right away. In this article, we unpack the common causes why this happens and provide you with solutions such as how to reset HVAC system and more.

Hot air blowing from your air conditioner can stem from several different reasons like your air filter or thermostat or it could be something more extensive. The issue could be as simple as fixing your thermostat or changing your air filter, however, it could also require you to call an HVAC technician to take a look and resolve the issue with more experience and tools.

AC Blowing Warm Air Blog

1. Dirty Air Filters

Every particle of air that travels through your home is first passed through your air filter. Air filters are responsible for blocking pathogens and other toxic fragments from circulating through your air by trapping them within its fibers. These filters can become clogged and dirty over time which can cause your system to overwork leading to AC unit malfunctioning. Changing your air filters every 90 days or 3 months will ensure that your system runs at a higher efficiency and doesn’t lead to any bigger problems.

2. Defrost Evaporator Coils

Oftentimes your evaporator coils and air filter can go hand in hand where if dirty air is being circulated from lack of proper filtration, your evaporator coils will begin to collect dust and dirt as well restricting their ability to cool the air properly.

One of the problems that can affect the function of the evaporator coils would be the moisture that builds on the coils. This moisture will begin to freeze over the coils if there is a clogged condensation drain. One of the solutions to HVAC blowing hot air would be to turn off your unit, clean the condensation drain, and allow the coils to defrost before turning the system back on.

3. Low Refrigerant Levels

Another one of the common causes that your AC unit could be blowing warm air could be either low refrigerant levels or a leak. Refrigerant is the operator behind the heat-cold exchange so when the levels are low or non-existent because it is leaking, your AC will be unable to produce cold air at all. Some of the factors that could be contributing to the unit having under or overcharged refrigerant levels include a worn service valve, loose joints, or poor assembly.

A few other indicators that the problem could be coming from your refrigerant levels besides the fact that your unit is blowing warm air is a hissing/gurgling sound or ice on your refrigerant line. These are all signs that your unit needs immediate attention. Refrigerant/coolant is a dangerous chemical that should be handled with care strictly by an HVAC technician. Alpha Mechanical has many experts to address your HVAC tune-up in Sacramento. If your air conditioner is blowing hot air on a consistent basis and you believe that your refrigerant is to blame, there could be corrosion as a result of leakage.

4. Malfunctioning or Restricted Compressor

The refrigerant and the compressor go hand in hand in the operation of your HVAC unit. If the compressor in your unit breaks down it will prevent the refrigerant from moving along the process of turning the gas into a liquid to chill the air.

Another issue that could come as a result of a restricted compressor would be if there is dirt and debris which could limit its ability to turn the HVAC unit on properly. If the condenser coils within the outdoor unit are covered in debris, the cooling coils will not be able to modify the temperature of the air to the desired indoor air temperature.

5. Incorrect Thermostat Settings

One of the more common incidents when an air conditioner is running hot is a simple thermostat look over and adjustment. Rather than have the thermostat setting to “on” or “fan” you should switch it to “auto” because this will allow the AC to run a cooling cycle when needed instead of constantly running which can lead to the air feeling warmer as a result.

If your thermostat is one that takes batteries, the simple fix to this problem would be to change the batteries first. It may also be time to update your thermostat. When your thermostat display is not working altogether, it is time to get an expert involved.

6. Leaks in Ductwork

It is the job of the ductwork to circulate and transfer all the air from your unit throughout the vents of your home. As a result of the location of your ducts typically being in your attic or walls, hot air can creep into any crack or leak and be moved throughout your home.When there is a leak within the sealing of the ductwork, the warm air surrounding the pipes will mix in with the cold air that is attempting to flow through, leaving your home with warmer air than expected. Ductwork troubles should be handled strictly by an HVAC professional and should also be cleaned and/or replaced every 3-6 years.

7. Replace an Aging Air Conditioner

If you are following the suggested guidelines for maintenance and routine care for your HVAC unit and you are still experiencing trouble with its heating or cooling ability, that is a sign that you need to consider your replacement options. The average lifespan of an air conditioning unit is between 15 to 20 years, however, it is primarily based upon units which have been kept up with routine maintenance. The older your unit is the less efficient and cost effective it becomes. Replacing air filters and scheduling semi-annual maintenance appointments with your local HVAC company will prolong the lifespan and performance of your unit. At Alpha Mechanical we specialize in a number of different HVAC services in Sacramento and offer to walk you through any replacement or maintenance question you may have.

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How to Reset an Air Conditioner and When You Need it?

The most common objective to resetting your air conditioner is to correct the home AC blowing warm air issue. If you feel hot air coming through vents when AC is off or when the thermostat is set to cool, keep reading for our solutions. If you have exhausted all of your efforts to fix the temperature of your air and your unit is still fairly newer, there could be a thermostat error that can be reset when your AC resets as well.

An additional reason for the air conditioner to require a reset is after a recent power outage. The protection circuit breaker in your AC unit turns on to prevent fires and blowup. In order to access your reset button, you might have to open your condensing unit. If you have a warranty, double check that your warranty guidelines do not require you to hire an HVAC professional to diagnose and handle your condensing unit.

While learning how to reset air conditioner can be a simple task, if you are uncomfortable messing with your HVAC unit, you may want to call a professional technician to come and help with how to reset AC unit. However, if you are familiar with how your air conditioner works, follow these instructions:

1. Turn off your AC unit in all areas:

Power down your thermostat by switching it to off. Once you have turned off the AC from the inside, Move to your circuit breaker panel and shut down the breaker that powers your HVAC. Some air conditioning units have a power switch in an electrical box near the outside unit.

2. Locate and hold the reset button:

Near the power switch on the outside electrical box either separate or attached to the unit itself, the AC reset button will be a small red button that you will need to press for roughly 3 to 5 seconds.

3. Restore power to your AC:

Turn all of the switches back to the “on” position starting with your breaker. Make sure that your thermostat is set to “cool” and adjust the settings to a lower temperature than the thermostat currently reads in order to begin a new cycle. After a few seconds, your air conditioner should start up. Once it does, you have successfully grasped how to reset HVAC.

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Get Help from an AC expert in Sacramento

No homeowner appreciates when their AC blows hot air. It can be tricky business to try to troubleshoot the problem yourself. If you have begun the troubleshooting process working through the list above attempting to resolve your air conditioner on your own and get stuck, it is time to call a professional.

No matter what kind of air conditioning issue you are facing, Alpha Mechanical is here to serve the Sacramento area with all of your HVAC needs including AC installation in Sacramento should you be ready to purchase a new unit.

Frequently Asked Questions

Why does my AC blow hot air?

There are several different reasons your AC could be blowing hot such as dirty air filters, evaporator coils, refrigerant leak, ductwork, thermostat, etc. It also may be time for AC repair in Sacramento if your system is beginning to show signs of aging.

How do I fix my AC blowing hot air?

Learning about the areas that could cause your AC to blow warm is the first step and then addressing which cause is second. You could even start by resetting your air conditioner to see if that solves the issue right off.

Where is the reset button on the air conditioner?

Look for it first around the exterior of the outside unit either near to the top or bottom of the system. The button will be small, red and easy to spot. Another spot to look is on the inside of the service panel located near or on the side of the air conditioner unit.

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