Having your air conditioning system not work properly can be incredibly frustrating. This is especially true when your system suddenly starts blowing warm air instead of cold. If you’re experiencing this issue, it may be caused by any one of the following issues.

How Air Conditioning Works

Before getting into the possible causes, it’s first important to understand how your AC system works. This will make it easier to see why some issues can cause your AC to produce hot air. Many people wrongly believe that an air conditioning system produces cold air, but this isn’t the case. Instead, air conditioning works by absorbing heat from inside the home and transferring it outside. The process works using cold refrigerant to capture heat from the air.

The condenser unit outside the home supplies cold refrigerant liquid to the evaporator coil located within the air handler inside the house. The air handler then draws hot air in from the building and forces it over the evaporator coil where the heat is absorbed by the refrigerant. This heats the refrigerant, which increases the pressure and turns it into a hot gas that then flows back outside to the condenser. Next, the heat is released into the air outside the building, which turns the refrigerant back from a gas to a liquid state.

The system is basically a closed loop that is constantly pumping cold refrigerant into the building and taking the heat back outside. Similarly, your ductwork is also a loop with hot air coming in and cooler air going out. Any issues that disrupt these loops can impact the system and cause it not to work properly.

The System Has a Refrigerant Leak

The most common reason that an air conditioning system will blow hot air is that there is a refrigerant leak. When a leak is present, it reduces the pressure inside the system. In turn, this causes the temperature of the refrigerant to become even colder, which can cause the evaporator coil inside the house and the condenser coil outside the house to freeze.

The process of absorbing heat from the air causes condensation to form on the evaporator coil. When everything is working properly, this condensation drips into a drain pan and then into the condensate drain line and out of the home. However, if the refrigerant liquid is too cold due to a lack of pressure, the condensation will freeze on the evaporator coil. The same thing can also happen to the condenser coil.

When the system freezes up, it can no longer properly supply refrigerant to the air handler. As a result, no heat is absorbed from the air, which means that the air coming out of the supply vents is the same temperature as the air going into the return vent.

The biggest issue when the system freezes is that the condenser will still continue to run constantly since the thermostat is signaling that the temperature inside the home is too warm. If the problem isn’t fixed quickly, it can burn out the motor in the condenser and ruin the unit. This problem is not repairable, which means you’ll need to purchase and install a new condenser unit to get your AC back up and running again.

There Isn’t Enough Airflow in the System

The evaporator coil can also freeze up if there isn’t sufficient airflow coming into the air handler. If the air handler isn’t drawing in enough hot air, the refrigerant in the evaporator coil will get too cold and eventually freeze. This usually occurs because the air filter is clogged. When the filter gets clogged, it drastically reduces the amount of air that can flow through it and makes it impossible for the air handler to draw in enough hot air.

Luckily, this is an easy problem both to avoid and fix. If the coil is frozen, all you need to do is change the air filter and wait for the evaporator coil to fully thaw out before turning the AC back on. Furthermore, all it takes to avoid this issue is to make sure to regularly check the air filter and replace it whenever it looks too dirty.

The filter should be replaced at least once every one to three months. Every two or three months is normally fine during the times of the year when your air conditioning or furnace doesn’t get much use. Still, you should really be replacing the filter every three to four weeks during the hottest and coldest times of the year when your system runs for many hours every day.

The Condenser Coil or Evaporator Coil Is Dirty

The condenser and evaporator coils can also freeze up if they become too dirty, and the easiest way to avoid this issue is to have your system professionally maintained by an HVAC technician at least once a year. In most cases, you should have your heating system maintained every fall and your AC system maintained every spring.

You can also check and clean the coils on your own. For the evaporator coil, simply open the access panel on your air handler and use the brush head on your vacuum to gently suck out all the dirt from the chamber and off of the coils. For the condenser coil, you’ll need to remove the side panels from the unit and then do the same thing.

The condenser unit is especially prone to getting dirty or clogged since it sits outside the home. The unit has small vents and holes that allow it to release heat, but these vents also make it easy for leaves, dust and debris to get inside. The problem is especially common in areas with lots of poplars or other cotton-producing trees.

The Condenser Unit Is Malfunctioning or Doesn’t Have Power

The hot air blowing from your vents could also indicate that the condenser isn’t working properly or isn’t running at all. For instance, it could be that the fan motor or some other component is worn out and needs to be replaced. The issue could also indicate that your condenser simply isn’t turning on for some reason, such as if the breaker is tripped or it has some other electrical issue. In these situations, the fan inside your home will still run. However, the air coming from the vents will be hot since the condenser isn’t supplying cold refrigerant to the system.

The Thermostat Isn’t Working Properly

One final possibility is that for some reason or another the thermostat isn’t signaling the condenser to run. This could be because you accidentally turned it to heat or changed the settings, or it could also be that the thermostat is broken or malfunctioning.

Professional Air Conditioning Services and Support

If you’re experiencing any issues with your air conditioning system, Green Energy Mechanical Inc is ready to help any way we can. We have been providing exceptional cooling, heating, and plumbing services to customers in Canton and Norfolk County since 2008. Our expert HVAC technicians can repair and maintain all types of heating and cooling systems, and we also carry a wide selection of energy-efficiency equipment for when it comes time to replace your AC or furnace. We pride ourselves on our outstanding level of customer service, and we offer honest, up-front estimates on all plumbing and HVAC services. To schedule an appointment to have your air conditioning system looked at, give us a call today.

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