One of the most important key factors that will play a role and ensure that you get the maximum efficiency of your air conditioner and heating system is to replace your dirty air filter. A dirty air filter can obstruct air flow, it can reduce the amount of airflow across your evaporator coil and cause ice build up, loss of efficiency, and system performance loss! If your filter becomes dirty enough to cause ice build up on the evaporator it increases the risk of compressor damage due to liquid refrigerant migrating back to the compressor, which can turn into a costly repair. In the heating season it also very important to replace the filters, a dirty filter in the heating mode will also restrict airflow across the furnace burners which will cause your burners to over heat due to not enough airflow across the burners to create the desired heat exchange and have the optimal heat rise across the burners. Overheating the burners due to airflow restriction can over time cause hairline cracks on your burners which can then lead to carbon monoxide being blown into your home and conditioned space causing a risk of carbon monoxide poisoning risk. In a central air conditioning system filters are usually located in a filter rack in your house ceiling in a hallway, or along the return air duct area. Other common filter locations are in the bottom of your furnace in a closet, garage or on a wall return air register. There are several types of filters, some are washable and others like pleated filters and non-pleated filters must be replaced. Neglecting the replacement of your air filters will decline the performance of your system and decrease the lifespan of your central heating and air conditioning system. If you cannot locate your air filter hire a professional to ensure your system is operating as designed to do so and ensure your system has a filter installed.