Air Conditioning Repair Certification (ETI) Practice Exam

A dirty air filter significantly reduces cooling efficiency in an air conditioning system. When the filter is clogged with dust and debris, it obstructs the airflow that is essential for the system to operate effectively. This restriction means that the system struggles to pull in enough air to provide adequate cooling, leading to a decrease in the overall performance of the AC unit.

Without sufficient airflow, the evaporator coil can become too cold and ice up, which further reduces the system's efficiency and can lead to additional complications, such as overheating the compressor. Consequently, the air coming out of the vents will not be adequately cooled, making the system work harder to reach the desired temperature.

Additionally, the need for the unit to operate longer and harder than normal can lead to increased energy consumption. While this is a related effect, the primary reason a dirty air filter is detrimental is its direct impact on cooling efficiency. This illustrates the importance of regular maintenance, including timely replacement of air filters, to ensure that the air conditioning system continues to function effectively and efficiently.