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Why Does My Aircon Smell Bad?

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It can be extremely aggravating to come home to an aircon that is producing a foul smell the second you turn it on. This is because such an unpleasant smell can rob you of the comfortable feeling a cooling aircon should offer. 

It would be very remiss to ignore why your aircon is even producing a foul smell, to begin with. When this happens therefore, it is extremely important to have aircon servicing performed be it an aircon repair or aircon chemical overhaul.

Listed below are 10 possible reasons why an aircon smells bad:


  1.  Aircon Gas Leaks

A leak in your aircon’s refrigerant lines can cause the entire aircon system to produce a foul smell that is similar to acetone. Being exposed to such an aircon leak can be hazardous for you and your loved ones. It can also reduce your aircon’s performance and result in an increase in the overall cost of your utility bills. Hence, it is important for this aircon leak to be fixed quickly. 


  1.  Filthy Evaporator Coils

Cooling coils are used to absorb heat from the air and then cool them before they are released through the air ducts. If your aircon is producing a bad smell therefore, it is a likely indicator that there is an accumulation of dust and dirt on the cooling coils. In that case, it is important to have the coils cleaned by a professional aircon service provider to prevent the accumulation of mould.


  1.  Wrong Aircon Size


A good aircon system recommended by your aircon service provider should not be too big for your house. This is because an aircon system that is too large for your home will experience swift cooling cycles and prevent your aircon from dehumidifying the air. It also promotes the growth of mould on or around your unit and the surrounding area. This can result in your house having a musty smell.


  1.  Clogged Aircon Filter


Air filters are supposed to remove pollutants from the air in your home. When these become clogged however, some of the pollutants that stick on your filter could produce a foul smell which could permeate around your home. If you want to eliminate this smell, you will have to either replace or clean your aircon filter. Alternatively, you can have an aircon chemical overhaul performed to thoroughly clean your aircon and remove any lingering smell and pollutants. 


  1.  Dead Animals In Aircon Vent


If your aircon smells especially at the beginning of summer, it could be caused by dead animals in your aircon’s vent. When you are looking for the source of the bad smell, therefore, you should check if there are any dead animals in your air ducts. If there are any, you can use tools such as kitchen tongs to remove them. Otherwise,, you can engage an aircon maintenance company to remove them for you. 


  1.  Too Much Moisture In Air Ducts And Vents


High humidity levels or leakages in the drain will cause more moisture to form in your aircon’s ducts and vents. If your aircon is producing a musty odour, it is highly likely that mould and mildew is infested in these areas. It is also important to remember that exposure to mould poses respiratory problems. In order to solve aircon leaking problems, you should clean and repair your aircon regularly. This also helps to remove moulds from your aircon ducts and vents. Hence, you should consider investing in a quarterly aircon servicing package


  1.  Frozen Evaporator Coils

Your aircon circulates cold air by absorbing warm air, removing its humidity, and cooling it before releasing it through the return vents. It is important to have clean filters for this process in order to ensure unrestricted airflow. Take note that pollutants such as dirt on the filters can restrict airflow which in turn can lead to water drops accumulating on the evaporator coils. These water drops can then freeze as the refrigerant continues to cool the air. As such, make sure to replace or clean your filters every few months.


  1.  Defective Central Motor

If you notice a smell coming from your aircon’s exhaust even though it is not powered by gas, it might be because your aircon’s internal motor is damaged due to wiring or overheating issues. When this happens, you should turn your power system off to prevent further damage. 


  1.  Clogged Condensate Drain

A common cause for a bad aircon smell is the congested condensate drain. A condensate drain is meant to collect condensation that drops from the cooling coils and drain it. When it becomes clogged, however, it creates an environment for mould and mildew to grow which can result in an unpleasant smell. 


  1.  Damaged Drain Tray


Every inverter or non-inverter aircon has a drain tray used to drain accumulated water. That said, this drain tray is susceptible to wear and tear and can become unusable when it is unable to drain water. Furthermore, it can become a breeding ground for moulds as a result which could lead to a foul aircon smell being produced. 



There are multiple reasons why your aircon might release a foul smell. Examples include an aircon gas leak, dirty evaporator coils, and having the wrong size of aircon. Other possible factors are a clogged aircon filter, dead animals in the aircon vent, too much moisture in the ducts and vents, and frozen evaporator coils. A defective central motor, clogged condensate drain, and damaged drain tray are other possible reasons. 

If your aircon emits a foul smell you can perform aircon troubleshooting yourself or hire aircon servicing professionals like Everyworks Singapore to assist you. We can fix your smelly aircon issues and perform other aircon services at affordable prices


Everyworks Singapore gives you the quickest solution to resolve all home maintenance issues faced by the busy modern individual. Fast response, fast arrangements and quality workmanship at reasonable and affordable prices As a leading trusted service provider in Singapore, we have served over 20,000 customers delivering outstanding service with hundreds of highly-rated reviews of our professional plumberelectricianaircon servicing technicians and handyman teams. Read through our articles and browse our past works to find out more about our home services in Singapore. To find a quick solution to your home repair woes, contact our dedicated and fast response customer support with a picture or a quick text either by Whatsapp at +65 82410032 or calling us at +65 6909 0990. For email enquiries, send it to


This article is reproduced from DW Aircon Servicing Singapore.

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