If your house air conditioner is emitting a sweet smell only when it's reaching the set temperature, it's possible that there is a specific condition or circumstance causing this issue. While it may not necessarily indicate a major problem, it's essential to understand the potential reasons behind the sweet smell. Here are a few possibilities:
Condensation buildup: When your air conditioner is cooling the air, it removes moisture from the air through condensation. If the condensation is not draining properly or there is excess water in the system, it could lead to the growth of mold or mildew, which can produce a sweet or musty smell. This smell might become more noticeable as the AC reaches the set temperature and the cooling cycle slows down.
Dirty evaporator coils: Over time, the evaporator coils of your AC can accumulate dirt and debris. When the AC is operating, this buildup can be exposed to the cooling process, leading to a sweet or moldy smell.
Microbial growth in the ducts: If there is microbial growth, such as mold or bacteria, within the ductwork or near the vents, the smell could become more pronounced when the AC is operating and pushing air through the system.
Refrigerant leak: While refrigerants are generally odorless, some leaks can produce a slightly sweet scent. If the refrigerant is leaking, the smell might become more noticeable as the AC operates and the cooling process intensifies.
Dirty air filters: A clogged or dirty air filter can trap dust, debris, and even mold, which can lead to a noticeable smell when the AC is running.
Contaminated drain pan: The drain pan located under the evaporator coils can collect dirt and organic material over time. This could result in a sweet smell being released when the AC is in use.
Since the technician you called didn't find any issues during their inspection, it's possible that the smell is subtle or intermittent, making it challenging to detect during a brief visit. If the smell persists and becomes bothersome, you might consider the following steps:
Change air filters: Replace the air filters regularly to ensure proper airflow and reduce the likelihood of odor-causing particles circulating through the system.
Check the drain pan and condensate drain line: Ensure that the drain pan is clean and that the condensate drain line is clear and not clogged. This will help prevent standing water and microbial growth.
Clean the evaporator coils: If the coils are dirty, consider having them cleaned by a professional to eliminate any odor-causing buildup.
Inspect ductwork: Have the ductwork inspected for signs of mold or microbial growth. If necessary, have it professionally cleaned and sanitized.
Monitor for refrigerant leaks: Keep an eye on your AC unit for any signs of refrigerant leaks, such as reduced cooling performance or hissing sounds. If you suspect a leak, contact a qualified HVAC technician for inspection and repair.
Use an air purifier: Consider using an air purifier with a HEPA filter to help remove odors and particles from the air.
If the smell persists despite trying these measures, it may be worth calling another HVAC technician for a second opinion or requesting a more thorough inspection. A persistent sweet smell could indicate an underlying issue that needs attention.