There are two types of coils within your ac system evaporator coils which are inside the indoor unit and the condenser coils which are found within the outside unit. Both play important roles in your system. The indoor coils help cool the air that passes over it. This coil condensates and can cause dust and other fine particles to stick to it and in some cases mould growth can be present. If we feel the coils need to be cleaned then we will inform the customer and then we will clean them with our jet and fogging machine spraying envirocon bio-cide over the coil. the outside unit which is normally located on the roof can also become clogged with dirt and dust which can affect the cooling system. once the fan removed we will cover any electrical parts then jet wash the coil fins down, which will help remove all the dust and dirt that has build up over time. once cleaned it allows your system to run more efficiently.