Why Is My AC Blowing Warm Air? Common Issues and Solutions
If an AC system is cooling properly, the conditioned air it puts out should be around 15-20 degrees cooler than the temperature in the house. Warm air blowing out of your vents is always a sign of a problem. There are several possible reasons why an AC will blow warm air, and sometimes the issue might be something you can fix yourself if you know what to check for.
Dirty Air Filter
The first thing to do if your AC is blowing warm air is to check the air filter to make sure it’s not too dirty. You normally want to replace the air filter in a central AC system every two to three months, if not more often. A dirty filter greatly hampers AC performance by restricting how much air the blower can draw into the system. That means you end up with weak airflow coming out of your vents.
Wrong Fan Setting
Most thermostats have two fan settings—On and Auto. When you’re using your air conditioning, you should always have the fan set to Auto. When it’s on this setting, the fan will only run when the outdoor unit is on. If you have the fan turned on, the system may push warm air into your house.
Low Refrigerant Level
All AC systems require a certain refrigerant charge or level to work properly. The issue is that a system can sometimes lose refrigerant over time as a result of leaks or a loose connection. As the refrigerant level decreases, it leads to a reduction in cooling capacity and a drop in performance. If the refrigerant level gets too low, the system may not be able to cool at all. That means the fan will just continually circulate warm air.
In some cases, a technician may just need to recharge the system so that it again has the correct refrigerant level. However, this won’t be possible if they determine the system has a leak, as they’ll first need to find and fix the leak before they can add more refrigerant.
Dirty Condenser Coil
The condenser coil in an outdoor unit is what allows an AC system to release the heat the refrigerant captured from inside the house. How it works is that heat continually flows out of the refrigerant into the air blowing over the coil. This process happens naturally as a result of the air being quite a bit cooler than the refrigerant.
The problem is that the condenser coil commonly gets covered in dirt, dust and debris, which can lead to a fairly significant reduction in cooling capacity and performance. The issue is that the dirt and dust act like insulation, blocking the air the condenser fan draws in from reaching the coil. The result is that the refrigerant retains quite a bit of heat when it gets pumped back inside, which prevents it from capturing nearly as much heat as it moves through the evaporator coil.
You can safely clean the condenser coil yourself by hosing it off with water, but this method isn’t always that effective. Instead, the better option is to have a technician service your AC system each year, as one part of this involves fully cleaning the condenser coil.
Frozen Evaporator Coil
AC evaporator coils are prone to freezing under certain conditions or when various issues are present. The coil will commonly freeze if the system is low on refrigerant. Insufficient airflow due to a dirty air filter or a malfunctioning blower can also lead to the condensation that forms on the coil freezing. The coil can freeze if it’s too dirty as well, due to not enough warm air blowing directly on it.
Once the coil begins to freeze, all the ice creates a barrier that blocks the warm air from reaching it. That means the refrigerant won’t be able to remove any heat from the air, resulting in the air still being warm when it blows out of the vents.
Leaving your AC running when the evaporator coil is frozen is a huge risk, as it can result in the compressor burning out. Should this happen, you’ll typically need to replace the entire outdoor unit. That’s why it’s important that you call an HVAC company immediately if your AC starts blowing warm air and you can’t figure out why.
For top-notch cooling and heating services in Asheville, NC, look to the experienced team at 1st Choice Service Group Heating & Air. Our NATE-certified technicians service all makes and models of HVAC equipment and can quickly get to the bottom of any issue you’re experiencing. To schedule a service call and get your AC checked out, contact us today.