What Causes Aircon Coil Corrosion and How to Prevent It

Air conditioning systems keep our homes and offices cool, especially during hot weather. Over time, however, components like the aircon coil can become damaged, with aircon coil corrosion being a common issue. If left untreated, corrosion can reduce efficiency, increase energy use, and lead to costly repairs. In this article, we’ll explore the causes of aircon coil corrosion and offer tips to prevent it, ensuring your system stays in top shape.

What Are Aircon Coils and Their Role?

Before delving into the causes of aircon coil corrosion, it’s important to understand the role of coils in your air conditioning system. An air conditioning system typically has two types of coils: the evaporator coil and the condenser coil.

Evaporator Coil: Located inside the air handler, the evaporator coil absorbs heat from the indoor air. As refrigerant flows through the coil, it absorbs heat, cools the air, and evaporates into a gas.

Condenser Coil: Located outside the home, the condenser coil releases the heat absorbed by the evaporator coil. The refrigerant in this coil is pressurized, turning it into a hot gas that releases heat to the outside air.

Both coils are vital for the heat exchange process that cools your home. However, over time, exposure to air, moisture, and other factors can lead to aircon coil corrosion, which can hinder the efficiency of your air conditioning system.

Causes of Aircon Coil Corrosion

Several factors contribute to aircon coil corrosion, ranging from environmental conditions to poor maintenance. Let’s explore the most common causes of coil corrosion.

1. Moisture and Humidity

Air conditioning systems operate by circulating air and refrigerant, both of which are often accompanied by moisture. The evaporator coil, which works in an environment with high humidity, is particularly vulnerable to aircon coil corrosion due to the constant exposure to moisture. Over time, the moisture can cause the coils to corrode, leading to leaks and poor performance.

If the evaporator or condenser coil is exposed to excessive moisture, it creates an ideal environment for rust and corrosion to develop. This is why areas with high humidity, like coastal regions or regions with heavy rainfall, are especially prone to aircon coil corrosion.

2. Environmental Pollutants and Chemicals

The environment in which the air conditioning unit operates can have a significant impact on aircon coil corrosion. Pollutants in the air, such as dust, dirt, and chemicals, can accumulate on the coils and cause damage over time. This is especially true in industrial areas or places with high pollution levels.

More specifically, airborne chemicals like chlorine, salt, and sulfur can accelerate the corrosion process. Salt from sea air is a major contributor to aircon coil corrosion in coastal regions. When salt particles settle on the coils, they create an acidic environment that accelerates the rusting process, weakening the coil material.

3. Improper Maintenance

A lack of regular maintenance is one of the primary causes of aircon coil corrosion. When an air conditioning system isn’t cleaned or serviced properly, dirt and debris can build up on the coils, obstructing airflow. This reduces the coil’s ability to dissipate heat and increases moisture retention, which encourages corrosion.

Additionally, without proper maintenance, refrigerant levels can drop or become unbalanced, which can put extra strain on the system. Over time, this can lead to excessive wear and tear on the aircon coil, resulting in corrosion or other forms of damage.

4. Acid Rain and Environmental Factors

Acid rain, a form of precipitation that contains high levels of sulfuric and nitric acids, is another factor that contributes to aircon coil corrosion. Acid rain occurs when pollutants like sulfur dioxide and nitrogen oxides from burning fossil fuels mix with water vapor in the atmosphere. When acid rain falls on the coils, it can cause rapid deterioration, especially in condenser coils that are exposed to the outside environment.

In areas prone to acid rain, the corrosive effects can be significantly worse, leading to the degradation of the aircon coil and a decrease in overall system efficiency.

5. Use of Low-Quality Materials

The material used in the construction of the aircon coil can affect its susceptibility to corrosion. Some older systems used coils made of materials that are more prone to rusting and corrosion, such as copper or steel. While these materials are still commonly used, newer air conditioners may use aluminum coils, which are more resistant to corrosion but not completely immune.

If the air conditioning unit is made of low-quality or inferior materials, the likelihood of aircon coil corrosion increases. Investing in higher-quality materials can help reduce the chances of corrosion in the long term.

How to Prevent Aircon Coil Corrosion

Now that we know the causes of aircon coil corrosion, it’s important to discuss how to prevent it. Regular maintenance and some practical steps can help protect your air conditioning system from corrosion and ensure it operates at peak efficiency.

1. Regular Cleaning and Maintenance

The most effective way to prevent aircon coil corrosion is to schedule regular maintenance for your air conditioning system. This includes cleaning the coils, changing the filters, and checking for any signs of wear or damage. HVAC professionals will also inspect the system for any signs of refrigerant leaks, rust, or corrosion on the coils, ensuring that potential problems are addressed before they worsen.

2. Keep the Coils Clean

Over time, dirt, dust, and debris can accumulate on the aircon coil, obstructing airflow and leading to corrosion. To prevent this, clean the coils regularly. If you are comfortable with basic maintenance, you can use a soft brush to remove debris from the coils. However, it’s always a good idea to have a professional HVAC technician clean the coils at least once a year to ensure thorough cleaning.

3. Install a Corrosion-Resistant Coating

Many modern air conditioners come with a protective coating on the coils that helps prevent corrosion. This coating acts as a barrier against moisture, pollutants, and harsh environmental factors. If your system doesn’t have this coating, you can ask your HVAC technician to apply one. This simple addition can extend the life of the aircon coil and help prevent rust from forming.

4. Monitor Humidity Levels

Since high humidity contributes to aircon coil corrosion, it’s important to control the moisture levels in your home. You can use a dehumidifier to help manage indoor humidity levels, particularly in areas prone to moisture buildup. Keeping the air dry can reduce the amount of moisture that comes in contact with the coils, minimizing the chances of corrosion.

5. Install a Salt-Free Air Filter (for Coastal Areas)

If you live in a coastal area where salt from the sea is a significant concern, consider installing a salt-free air filter or a protective cover for your air conditioning unit. These filters can help prevent salt from entering the system and settling on the aircon coil, reducing the likelihood of corrosion caused by salty air.

6. Use High-Quality Materials

When purchasing a new air conditioning unit or replacing components, opt for high-quality materials that are resistant to corrosion. Aluminum coils, for example, are more corrosion-resistant than copper coils and can provide better long-term durability.

Aircon coil corrosion is a serious issue that can affect the efficiency and lifespan of your air conditioning system. The causes of corrosion range from environmental factors like humidity and pollutants to poor maintenance and low-quality materials. 

However, by understanding the causes and implementing preventative measures, such as regular cleaning, installing protective coatings, and controlling humidity levels, you can significantly reduce the risk of corrosion and ensure your air conditioning system runs smoothly for years to come. Regular maintenance by an HVAC professional remains the most effective way to keep your aircon coil in top condition and avoid costly repairs.