Chemical cleaning is a more intensive aircon cleaning method that uses specially formulated cleaning solutions or foaming agents to dissolve stubborn dirt, mold, grease, and bacteria that cannot be removed by water alone during a standard wash. The technician applies the chemical solution directly to the evaporator coil and other internal surfaces, allows it to penetrate and break down the buildup, and then rinses the components thoroughly to remove both the cleaning agent and the loosened contaminants. Chemical cleaning is more effective than standard cleaning for units with moderate to heavy soiling and is recommended when a general wash no longer restores adequate cooling performance or when visible mold growth is present inside the unit.