Which condition can lead to decreased efficiency in an HVAC system?

Decreased efficiency in an HVAC system can result from dirty air filters. When air filters become clogged with dust, dirt, and debris, they restrict the airflow throughout the system. This obstruction forces the HVAC system to work harder to pull air through the filters, which can lead to increased energy consumption and higher utility bills. Additionally, reduced airflow can cause the system to run longer than necessary, potentially leading to overheating and premature wear on HVAC components. Maintaining clean air filters is crucial to ensure optimal airflow and efficiency, allowing the system to operate effectively and prolong its lifespan.