AC Blowing Warm Air in House: 8 Possible Reasons and Solutions

Having air conditioner problems during summertime is an experience you will never want to undergo. If you live in Arizona, for example, the last thing you want while riding out the hottest days of the year is to have your AC blowing warm air in house instead of the cool breeze that you badly crave. With the temperature reaching 110 degrees from June to August, you will definitely need your unit working and in tip-top condition. Unfortunately, this is a common airflow issue.

To avoid this inconvenience, it pays to know the usual causes of air conditioner problems. There are easy steps you can take to prevent these setbacks from happening in your home or business space. Just like the other appliances, your AC unit needs to be monitored and regularly cleaned to avoid issues. This way, you may never have to deal with an AC unit blowing warm air at the height of summer again.

My AC is Blowing Warm Air: 8 Possible Reasons and What to Do

Warm air coming from your air conditioner on a humid day makes staying in your home simply unbearable. More often than not, the best way to solve this predicament is to ask help from a professional. Check out these AC specialists in Phoenix, AZ. Some of the problems in your AC unit can easily be solved. You may just have to change the air filters or hose down your outdoor unit. Others are more difficult to work out, like leaking ducts and replacing refrigerants.

Low Refrigerant

One of the most common causes for AC blowing warm air is low refrigerant. A refrigerant is essential to maintain your unit’s best performance. It is the fluid that absorbs heat and humidity from the air. If your AC is not cooling, it may be because the refrigerant is leaking and whatever is left is not enough to effectively keep your home cool.

Unfortunately, fixing this is not as simple as replacing the refrigerant. Finding the leaks and repairing holes can be time consuming and expensive. If not promptly fixed, it may even cause damage to the compressor motor. Some of the tell-tale signs of a leaking refrigerant are hissing or bubbling noises and a buildup of ice on the outside unit.

Solution: If you suspect that the low refrigerant in your AC is due to a leak, call your technician right away. A leaking refrigerant is a health and safety hazard, so it is important to have it fixed as soon as possible.

Thermostat Problems

If you detect your home AC blowing warm air, it may be due to problems in the thermostat. This frequently happens to old dial-type units when they are calibrated incorrectly. If you still have the air conditioner manual, check if your thermostat settings are correct. If the problem persists, you may have your thermostat replaced or recalibrated. 

You can always do some troubleshooting to see if the settings in your thermostat are wrong. This works for both split and window AC. Turn the settings to “auto” mode instead of “on” mode. This way, the fan will work only when the air is being cooled. Also, double-check if you might have accidentally flipped the thermostat to heat mode. This is a mistake that is frequently overlooked.

Solution: Consider a programmable thermostat. Older control systems tend to malfunction easily. With a programmable one, you can keep the temperature inside your home consistent every time. Your energy savings will make the price of getting one worth it.

Dirty Air Filters

This is the most common reason why your air conditioner is not cooling properly. Clogged air filters can cause various problems in your unit. It can even interfere with how your thermostat works. If the filter is dirty and unclean due to dust, the passage of cool and warm air inside the ducts is blocked. This then leads to the evaporator coils freezing, resulting in your house AC blowing warm air. This is why replacing your air conditioner filters regularly is such an important aspect of maintenance.

Solution: An AC unit running on clean filters can keep on operating smoothly for a longer time. It can also lower your energy costs. Clean or replace your dirty filters at least every three months or as needed.

Frozen Evaporator Coils

Another cause of home AC blowing warm air is frozen evaporator coils. Filled with refrigerant, these coils act like a sponge and soak up heat from the air. Without proper airflow, the evaporator gets too cold, resulting in ice buildup. When this happens, your unit will release warm air, or sometimes no air at all. It is important that warm air gets to circulate around the coils for them to work properly.

Solution: Dirty air filters lead to dirty and frozen evaporator coils. However, while filters are easy enough to replace by yourself, you need an AC specialist to clean the coils. Do not attempt to remove them, as they can easily be damaged by improper handling.

Dirty Condenser Coils

Your air conditioner’s condenser coils are responsible for removing heat from air and expelling it outside your house. As part of the outdoor unit, they are frequently exposed to the elements and over time, dirt and grime accumulate on the coils. This impedes heat transfer. You will start noticing this with your AC blowing warm air in the house. The dirty coils put undue strain on the entire unit, leading to increased wear and tear on parts.

Solution: Clean the outdoor unit regularly to give your condenser ample room to breathe. Remove weed and debris surrounding the unit and hose it down to remove caked-up dirt. Do not forget to shut off the power before cleaning.

Fan Problems

There are several reasons why the fans in your AC unit do not work properly. It could be because of a faulty motor, worn belts, or lack of lubrication. Dirt and debris can also cause problems in the fans. If the fan, either on the indoor or outdoor unit, fails to work as it should, this will facilitate poor airflow. This then leads to your AC blowing warm air instead of the cool ones you expect. If neglected, fan problems may result in compressor failure. 

Solution: Check if the fan motor has to be replaced or just needs a good cleaning. If it is still going, but with speed reduced, call a professional service person and have it checked. For dirty blades, you can clean away any debris and dirt using a vacuum and a soft cloth.

Leaking Ducts

If there is a sudden climb in your energy bills this summer, you may want to check on your home’s ductwork. There may be a leak you have not noticed, probably caused by rodents or careless workers during installation. Ducts run through your walls and ceilings, carrying the cooled air from your AC unit throughout your home. If there are holes in the ducts, the air winds up inside the walls, a scenario you will not want to happen.

Solution: Install an overflow switch. It shuts down the entire system once a water leak is detected, saving you a lot of stress. Call your AC specialist so they can inspect the ducts, do repairs and block holes if there are any.

Clogged Drains

Another reason for my ac blowing warm air is clogged drains. The moisture that the AC removes from the air is supposed to be expelled through a drain line. If this line gets blocked due to debris or dirt, the water can go back and damage the AC’s system. In a worst-case scenario, the water leaks and goes through the walls and ceilings, as well as furnishings. This leads to mold growth if not discovered right away.

Solution: Some clogs are relatively easy for you to fix. If the blockage is visible when you look at the drainpipe, you can remove it manually wearing protective gloves. You can also use a vinegar solution once a month to avoid any build up in the drain lines.

Almost all the causes of air conditioner problems can be prevented with regular maintenance. Aside from extending the lifespan of your AC, it can reduce your energy bills by improving your unit’s energy efficiency. Have your AC technician tune up and inspect your system every spring, before powering it up for the first time. With this, you will never have to experience your AC blowing warm air in the house when summer comes.

Frequently Asked Questions

Why is my AC blowing warm air?

There are many possible reasons your air conditioner could be blowing warm air. One of the most common explanations would be that the unit is running low on refrigerant. You may also have a thermostat problem or be dealing with a dirty air filter. Refer to the list above for more information about the other possible causes of an air conditioner blowing warm air.

What should the air temperature coming out of my vents be?

Generally speaking, the air coming out of your unit will be roughly 20 degrees cooler than the standing air inside your room. You shouldn’t necessarily take a deviation from this to mean that your air conditioner is malfunctioning, though; make sure you investigate more thoroughly.

What should I do if my air conditioner is not cooling enough?

Your first step should be to try and determine what could be to blame. Look at your refrigerant and thermostat first before moving on to your evaporator coils. If you haven’t cleaned the coils in a while, check out this post for some tips. When your air conditioner coils are covered in dirt and debris, heat may not be transferred out of your home properly.

How do you know if your air conditioner is cooling?

Place a thermometer near one of your registers. This will tell you whether your air conditioner is producing air roughly 20 degrees below the temperature inside your house. Again, you won’t want to use this as your only diagnostic method but it can be a good first step if you’re not sure whether something is truly wrong.

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