Has your air conditioning system suddenly started blowing hot air? When an AC system is working correctly, the air it puts out should be noticeably cooler compared to your home’s current temperature. Hot air obviously indicates that your AC isn’t cooling as it should and normally indicates that the system has one of the following issues.
Clogged Air Filter
We’d always recommend replacing the air filter in your AC system as the first step any time it starts blowing hot air. A dirty, clogged air filter is extremely restrictive, which means that very little air can flow through it. When your AC is on, the blower continually pulls in warm air via the supply vents and ductwork. The air then gets drawn through the filter before flowing into the air handler unit where the evaporator coil is located.
When your AC has sufficient airflow and is working properly, the air it puts out should be around 15 to 20 degrees cooler than the current temperature inside your house. That means it will feel noticeably cooler. If your AC filter is dirty, there won’t be nearly as much air flowing into the air handler as there should be. That also means you’ll have weak airflow coming out of all of the supply vents. The less air there is coming into the system, the less heat it will capture. This can result in the air coming out of the vents feeling somewhat warm since it will only be slightly cooler than the current temperature inside your house.
Dirty Coils
The evaporator coil inside your house is what enables the refrigerant in your AC system to capture heat. The refrigerant then transfers the heat outside to the condenser coil, which helps it to release the heat. If either of these coils is dirty and caked with dust, it can prevent the process from working properly. The issue is that the layer of dust insulates the coil’s tubes and fins.
If the evaporator coil is dirty, it makes it so that the refrigerant can capture little to no heat. If the condenser coil is dirty, the dust traps the heat and prevents it from being able to flow out of the refrigerant into the air outside. That means that the refrigerant will be much warmer than it should be when the compressor pumps it back inside the house to the evaporator coil. The higher temperature also greatly reduces how much heat the refrigerant can capture. The result if either of the coils is too dirty is that your AC won’t be able to effectively cool the air flowing through it. That means that the air coming out of the system will be about the same temperature as the air coming into it.
Dirty coils are a fairly common problem that results from a lack of maintenance. That’s because a technician will always fully clean each of the coils when servicing and maintaining an AC system. Ensuring that the coils are clean so that your air conditioning can cool effectively is just one of many reasons why annual AC maintenance is so important.
Refrigerant Leak
The refrigerant level in your AC system should always remain the same since it flows through the system in a closed loop. Nonetheless, AC systems are somewhat prone to developing leaks over time due to corrosion on one of the coils or somewhere on one of the copper refrigerant lines. If your AC is leaking, there will quickly come a time when it no longer has enough refrigerant for it to cool effectively. That means it will capture little to no heat, again resulting in the air it puts out being about as hot as the current temperature inside your house.
Fixing a refrigerant leak can be quite costly. The first step is for the technician to locate the source of the leak, which can take some time if one of the copper lines is leaking. In this case, the technician can usually just cut out the damaged section of the line and then splice a new piece of copper in its place. If either of the coils is leaking, the only option is to usually replace it. After locating the leak, the technician first needs to capture all of the refrigerant in the system. They’ll then need to recharge the system to the right level, which means you’ll have to pay for additional refrigerant.
Frozen Evaporator Coil
AC evaporator coils can freeze up due to any of the issues we just discussed. It can also happen if the system doesn’t have sufficient airflow for any other reason, such as ductwork leaks or a malfunctioning blower. When your AC runs, the evaporator coil is extremely cold. This results in the warm air coming into the system quickly cooling down to its dew point as it comes into contact with the coil. Once the air reaches its dew point, much of the moisture it contains condenses into water on the coil. Despite the coil being so cold, the water normally drips straight off of it because the warm air prevents it from freezing. Nonetheless, the condensation can quickly freeze if there isn’t enough warm air continually moving over the coil.
The reason that a refrigerant leak can cause the coil to freeze is that the pressure in the system is much lower if it doesn’t have the proper amount of refrigerant. As the pressure decreases so does the temperature of the refrigerant. That means that the refrigerant can get so cold that condensation on the evaporator coil freezes even if the system has sufficient airflow.
Determining if the evaporator coil in your AC system is frozen isn’t always easy. Some systems have an access panel or door on the air handler unit that you can open to see inside and check for ice on the coil. However, many systems are designed so that the air handler is completely sealed. That means the only way to open it up and access the coil is to cut a hole in it, which is definitely not something you should ever attempt. In this case, your best bet is to check for ice on the copper lines where they exit the air handler since they can sometimes also freeze.
What to Do If Your AC Blows Hot Air
Unfortunately, there’s not really much that you can do to determine why your AC is blowing hot air other than replacing the air filter. The one thing you could try when facing this issue is to shut your AC off, replace the air filter and then wait at least a few hours before turning it on. The reason you want to wait is just in case the coil is frozen since you need to allow it to completely thaw out before you try running your AC again. This is because serious damage can result if you try to run the system.
The fact that your AC can blow hot air for different reasons and that you don’t want to run it when it’s frozen is why you’re better off just contacting a repair service as soon as this issue arises. That way you hopefully won’t have to leave your AC shut off for hours and you can also quickly determine why it’s blowing hot air.
The experienced technicians at Home Comfort Solutions are ready to help if your AC is blowing hot air or has any other issues. We can repair any AC make and model, and we’re available 24/7 for any emergencies. Contact us today if you need an AC inspection or any other air conditioning or heating service in Moore or the OKC Metro area.
