Mold in Aircon – Causes And Solutions

Mold in aircon is a common problem for many people these days. Mold is a fungus that we can naturally find almost everywhere globally. And unlucky for us, there is no proper way to stop it from growing anywhere it wants to. Any area with enough moisture, humidity, and airflow will allow moss to grow.

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Since all three of these factors are sufficiently linked with aircon units, there is a good chance that mold might grow inside them. Any part of the aircon connected with the outside air is susceptible to mold growth. Thus, we must be extra careful during our aircon inspections. This is because once the mold grows, it can spread diseases.

Causes Of Mold Growth In Aircons

Before we get to the causes, we must know three factors essential for mold growth. These are:

  • Optimal temperature
  • Humidity
  • Nutrients

Any part of the aircon with these three available in the optimum amount will allow mold growth. The causes leading up to the development of these three factors in aircon include:

1.   Air Duct Leakage

Leakage of the air duct from the aircon into a closed area can promote mold growth. This closed area can be the aircon itself, a small attic, or an unkempt crawl space. These spaces are usually small, with enough moisture buildup to provide optimal conditions. The cold air adds to the effect, and mold grows readily.

This air leakage can occur in the outflow or the inflow ducts. Leakages in the inflow duct can bring dirty and moldy fumes from the outside into small spaces. This polluted air is a good source of nasty mold. This mold can grow in any place it finds.

2.   Dirty Filter

Unclean filters are another source of mold entering the aircon. Usually, filters trap all these nasty particles coming from the outside. This prevents any mold from getting entry to the inside. But whenever a filter is dirty and unclean, this trapping is not adequate. This ineffective trapping can cause the mold to escape the filter and enter the inside. Once inside, this mold can grow in any place, providing optimal conditions.

3.   Leaking Drainage Pipes

Water drainage pipes allow the water to flow from the aircon to the outside. Water cannot outflow effectively when debris or dirt accumulation clogs these pipes. This causes water to build up inside the pipes, which can also cause backflow. Through this backflow, water can enter the aircon and build up there.

This buildup in the aircon and the clogs in the drainage pipes promote mold growth. Thus, adequate water outflow must occur at all times to prevent any mold in AC.

4.   Poor Insulation On Refrigerant Lines

These lines are very thick, having proper insulation covering them. This covering traps the cold inside and prevents it from getting to the outside of the lines. But when any factor damages this insulation, the cold can get to the outside of the line. This cold gas can create a condensation film over the refrigerant line. This film allows mold in air conditioners to grow easily by providing adequate humidity and temperature.

Solutions To The Mold Problem

Now that we have looked at the causes, let’s explore some solutions.

1.   Allow Proper Air Flow

Maintaining functioning air ducts is one of the best ways to prevent mold. When the air ducts have a proper covering, the air stays inside and cannot escape. Without the air, mold can not grow. Thus we must take extra care to ensure that all air ducts are without leaks. We should check the inflow as well as the outflow ducts.

Mold in Aircon

2.   Cleaning The Filter Regularly

Regularly cleaning the filter and changing it after regular intervals can effectively prevent mold. Clean filters can easily catch mold as well as all other dirt particles. This not only makes the rooms cleaner and pollutant free but also prevents mold entry. You must know how to clean the mold as well as the filter.

3.   Allowing Proper Water Drainage

Good water drainage is essential to prevent water buildup inside the aircon. This reduces the chances of the aircon leaking water from the inside and also prevents mold. This is because, without water, the mold cannot find any humidity to survive. Thus we must check the water drainage pipes and ensure they are working well.

4.   Preventing Any Gas Leak

The refrigerant gas can leak from any part of its duct. This gas can be the source of condensation and humidity for mold growth. Thus, to prevent such leaks, we must check the gas duct regularly and ensure there are no leaks.


Mold in aircon can be a nasty problem to deal with. It can grow in all parts of the aircon itself and lower the unit’s function. Mold can also spread to the inside of the room and can cause allergies and breathing problems. Thus extra care of all parts of the aircon is essential. This care can prevent any leaks. Care can also reduce the chances of the conditions being optimal for mold growth.

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