Why Your AC Smells When You First Turn It On?

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When you first turn on your air conditioner, when the summer heat becomes too much to bear, you expect a light breeze to flow in your room and give you a cooling sensation. However, you might sometimes get an unpleasant odor mixed with the air. In this article, we will explore the reasons for the air conditioner’s smell.

Why is it Happening?

There are three main reasons for this pungent odor. However, the smell normally goes away after the first use, provided that the AC is well maintained.
  • Mold on the Evaporator Coil and Fins: When dirt, dust, and moisture collect on the indoor evaporator coil after long periods of inactivity. Mold can thrive in this type of atmosphere. For the first time in the season, air passes over the evaporator coil and fins, picking up the mold’s decomposing odor and carrying it into your home. Clean the evaporator fins with water and a few drops of mild detergent each fall to help prevent this stench. Before turning on your air conditioner for the first time in the spring, repeat this cleaning procedure.
  • Mildew on the Air Filter: Mildew growth is encouraged by dust, hair, and moisture on the AC filter, resulting in a musty odor when the air conditioner is turned on. If you don’t use forced-air heating in the winter, this is most likely why the air conditioner stank when first switched on. Clean or change the filter in the spring to help prevent this odor.
  • Algae and Mold in the Drain Pan: Air conditioners produce condensate as they remove extra indoor humidity. Mold and algae can grow in a drain pan due to the dampness. When you turn on the air conditioner for the first time, this can clog the drain and cause an unpleasant odor. Before turning off the air conditioner for the winter, empty the drain pan to help prevent an unpleasant stink. A simple wash with mild bleach removes any remaining odors for a fresh start to the cooling season in the spring.


Your air conditioner becomes a crucial part of your life during the summertime, and if it keeps smelling, you wouldn’t turn it on and would invariably start feeling hot. We at Cool Air Designs provide comprehensive air conditioning repair and maintenance and investigate any potential future breakdown issues and prevent them from occurring. It is self-evident that mechanical parts will wear out and produce a failure at some point. Maintenance may have delayed this catastrophe, but it can never eliminate the risk. We provide air conditioning repair services and much more in Babylon, Ronkonkoma, NY, and surrounding areas. We take our contacts with customers extremely seriously, and we work well with any other contractors who may be on the project. At all times, your satisfaction is paramount. For your and our safety, we are fully licensed and insured. Our A+ BBB rating has put us miles ahead of the competition.