Having your AC system only cool some rooms can be incredibly frustrating and is something that happens more commonly than you may think. If the issue only recently started occurring, there’s a chance you may be able to fix it yourself quite easily. However, there are also times when uneven cooling is a sign of a bigger issue with your HVAC system or ductwork.
Clogged Air Filter
If you find that you’re suddenly dealing with uneven cooling issues, the first thing you should do is check how dirty the AC air filter is. Clogged filters are extremely restrictive, meaning very little air can get drawn through them. Restricted airflow makes an AC system cool much more slowly, and it often results in only some rooms receiving cold air simply because the system isn’t putting out nearly as much air as it normally does. The further away a room is from the AC air handler, the less cold air it will receive. The rooms at the ends of the supply ductwork may not receive any air at all.
If the filter is covered in a layer of debris or is starting to turn dark, replacing it will improve airflow and help your AC to cool more evenly. You can also easily avoid this type of issue by replacing the filter every 30-90 days. In Eugene, you’ll often only need to replace the filter every three months due to your AC not running all that much. However, if you don’t keep up with dusting and cleaning your floors or have indoor pets, you may need to replace the filter every month or two.
Blocked Vents
When you have any rooms that aren’t getting sufficiently cooled, you should also make sure that any vents in that room aren’t clogged with debris and that the airflow isn’t blocked off by furniture or other items. If even a few vents are obstructed or clogged, it can lead to airflow issues in other rooms as a result of high static pressure (airflow resistance). What happens when supply vents are closed is that the cold air backs up in the supply ducts because there is more air coming into the system than can flow out. As the pressure increases, it then becomes more difficult for the blower to pump additional air into the supply ducts. The result is that the more central rooms usually receive more air, and the rooms further away receive almost no air.
You also want to make sure that the grille or cover on all of the return vents is free of dust and debris. Clogged return vents restrict airflow and can create the same issues as a clogged air filter.
Duct Leaks
Old or damaged ducts that have gaps or holes where air can leak out is another issue that will usually result in uneven cooling. The problem here is that cold air continually escapes, which can result in a significant decrease in the volume of air flowing out of the vents further along in the supply ducts. Not only can duct leaks lead to uneven cooling, but they also result in energy being wasted and the AC system not cooling as efficiently. If your ductwork is more than 20-25 years old, there’s a fairly high chance it has numerous leaks. The same is true if it’s been more than 10 years since you had your ductwork resealed.
Insufficient Duct Insulation
If you have any supply ducts in your crawl space or attic, it’s essential that they’re properly insulated. Attics are often at least 20-40 degrees hotter than outside during the summer, and crawl spaces can also get quite hot if not sufficiently ventilated. Insulation prevents the hot air in the attic or crawl space from heating up the metal ductwork. If the ducts aren’t insulated or there are any gaps in the insulation, the cold air will continually gain heat and become much warmer before it flows out of the vents. Uninsulated ductwork in an attic or crawl space can also have issues with condensation, which could lead to mold growth. While you could insulate the ducts yourself, it’s much easier just to have a professional do it.
Poor Ductwork Design
The size and layout of the supply and return ductwork have a major impact on how well the HVAC system works and how evenly it distributes air throughout the house. If the ductwork is too large, it will often result in only the closer rooms receiving sufficient air. The same can happen if there are too many bends or angles in the supply ducts where the air has to change direction.
Undersized ductwork can lead to weak airflow in almost every room and make the HVAC system much less energy efficient. Having the return ductwork be smaller than the supply ductwork also creates the same issues.
Another crucial factor is ensuring even airflow across the house is air balancing. This often involves using dampers in different parts of the supply ductwork that can be adjusted as needed to ensure that the same volume of air flows out of every vent. In some cases, a technician may be able to slightly open or close some of the dampers to rebalance the air and provide more even and consistent cooling. However, if your ductwork isn’t properly sized or is poorly designed, the only real option is to have at least some of it redone.
Undersized System
One issue that will always lead to significant issues in terms of uneven cooling is if your AC system is too small for your house. An undersized system simply won’t be able to put out enough cold air to supply every room. Unfortunately, the only thing you can do if your AC is undersized is to replace it.
Single-Zone Setup Limitations
Most homes have a single-zone HVAC system, which can create issues with uneven cooling. The main problem is that not every room cools down and heats back up at the same rate. For instance, rooms with skylights and large windows or those on an upper floor get hot faster, while rooms on lower levels tend to stay cooler.
Upgrading to a zoned HVAC system helps overcome these issues. A zoned system has multiple thermostats in different parts of the house, each of which independently controls the temperature in that area. That means each zone always gets exactly as much cold air as it needs to stay at the desired temperature.
Upgrading to a ductless mini-split system is a good option for ensuring you always have even cooling. In a mini-split system, each room has its own air handler connected to the same outdoor unit. The benefit is that you can cool every room independently, which provides even better results than a zoned central HVAC system.
Fix Your Cooling Problems Today
If you’re frustrated by uneven cooling or dealing with any other HVAC issues, Reynolds Electric, Plumbing, Heating and Air is here to help. We’ve been serving Eugene residents for the past 65 years and have a team of experienced professionals that can handle all of your repair, maintenance steps and installation needs. To schedule an inspection and determine what’s causing your AC to cool unevenly, contact us today.
