Many families notice a musty smell from their air conditioners upon startup, often attributing it to outdoor dust or dry air. However, air quality experts state the source originates within the indoor unit.
During operation, the indoor unit's low temperature causes water vapor to condense on its surface. If the unit is turned off immediately after use, this moisture does not fully drain and remains trapped in the enclosed space, creating a favorable environment for microorganisms to multiply.
Studies on microbial contamination in heating, ventilation, and air conditioning (HVAC) systems in Japan indicate that after 24-48 hours of moisture accumulation, common household molds like Cladosporium and Aspergillus can thrive and release spores into the air during the next startup, leading to sneezing, coughing, or respiratory irritation.
Beyond mold, abruptly cutting power by unplugging or flipping a circuit breaker while the unit is running can damage mechanical components. According to the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) in the US, disconnecting power when the unit operates at high capacity can cause liquid slugging, reducing compressor lifespan.
The compressor is the most critical component of an air conditioner, and its replacement cost can exceed 50% of a new unit's value. Many air conditioners used for 3-5 years develop loud noises or reduced cooling efficiency, which can stem from the habit of abrupt shutdowns, not necessarily natural aging.
Solutions
Before leaving a room, users should switch the air conditioner to fan-only mode for 5-10 minutes. This allows the airflow to evaporate residual moisture on the indoor unit, eliminating the damp conditions that promote mold growth.
Some new generation inverter air conditioners feature a built-in self-drying function (Internal Clean/Naibu Clean). When users press the off button on the remote, the louver does not close immediately; instead, the fan automatically runs for an additional 15-30 minutes to dry the interior before the unit completely powers down.
Adopting this proper operating habit does not significantly increase electricity costs. Instead, it reduces the frequency of cleaning and maintenance, and mitigates the risk of major compressor damage in the long run.
Bao Nhien (Source: Aboluowang)
