A BVS Worker Performing Maintenance on an open AHU With The Copper Coil Visible

Within the HVAC system, the AHU (Air Handling Unit) is a vital component that helps in regulating the air quality and temperature. Among the essential elements within it are the AHU cooling & heating coils, which are responsible for heating or cooling the air as needed. Over time, your coil can wear out, leading to decreased efficiency and potential malfunctions. In this article, we’ll discuss how to identify when your AHU coil may need changing and the steps to address this issue.

Common Issues

1. Reduced Cooling or Heating Capacity

One of the primary signs that your AHU coils may need changing is a noticeable reduction in the system’s cooling or heating capacity. If your HVAC system is struggling to maintain the desired indoor temperature despite regular maintenance, it might be time to inspect the coils. Damaged or deteriorating coils can significantly impact the unit’s efficiency.

2. Inadequate Airflow

Poor airflow through the HVAC system can also be an indicator of coil problems. Clogged or damaged coils can restrict the flow of air, causing your system to work harder to circulate air throughout your space. This not only decreases comfort but can also lead to higher energy bills.

3. Ice Formation

If you notice ice formation on or around the AHU coils, it’s a clear sign that something is amiss. Ice buildup can indicate a range of issues, including low refrigerant levels, clogged coils, or a malfunctioning defrost cycle. Addressing these problems promptly can prevent further damage to your system.

4. Uneven Temperature Distribution

Inconsistent temperature distribution throughout your space is another indication that your AHU coils may be in need of replacement. If some areas are excessively hot or cold while others remain comfortable, it’s likely that your coils are not functioning properly. This can lead to discomfort and decreased energy efficiency.

5. Unusual Sounds

Unusual sounds coming from your HVAC system, such as banging, hissing, or popping noises, can be a sign of coil issues. These sounds may result from the expansion and contraction of damaged coils or the buildup of ice. It’s essential to address these sounds promptly to prevent further damage.

6. Frequent HVAC Repairs

If you find yourself scheduling frequent repairs for your HVAC system, it could be a sign that your AHU coils are deteriorating. Replacing coils can be a cost-effective solution in the long run, as constant repairs can add up quickly.

7. Visual Inspection

Performing a visual inspection of your AHU coils can reveal telltale signs of wear and tear. Look for corrosion, rust, or physical damage on the coils. If you notice any of these issues, it’s a clear indication that replacement is necessary.

8. Increased Energy Bills

Higher energy bills with no change in your usage patterns can be a result of decreased HVAC system efficiency. As your coils deteriorate, your system needs to work harder to maintain the desired temperature, leading to increased energy consumption.


Maintaining your AHU coils is crucial for the overall performance of your HVAC system. By paying attention to the signs mentioned above and taking prompt action, you can ensure that your heating and cooling system remains efficient and reliable. Regular maintenance and timely replacements will not only keep you comfortable but also save you money on energy bills and unnecessary repairs.

If you want to learn more about AHU coil replacements, feel free to send us an email at info@bvs-ltd.co.uk or give us a call 01256 518170