Air conditioning systems use two sets of coils to cool your home: the condenser coils that are in the outdoor unit and the evaporator coils that are in the indoor unit (if you use a ductless cooling system, these coils will be inside the blowers). The coils play a major role in the heat release/cooling process, so it is important that they are well-maintained. During annual or bi-annual maintenance, they will be carefully and thoroughly cleaned. Otherwise, problems will ensue.