How to get rid of a bad smell from an air conditioner

Dealing with a bad odour from an air conditioner and the likely causes of it makes for a more pleasant experience, as bad odour is quite displeasing.


As much as air conditioners provide the cooling you need on a hot summer day, they can also come with unwanted problems that can be a huge inconvenience to you and your household. One such problem is when your air conditioner exudes an unpleasant odour.

If you notice that your home smells unpleasant and if it seems to be coming from your air conditioning unit, there may be a few issues with your air conditioner that you need to investigate. An unpleasant odour from cooling systems can be near unbearable to handle.

Bad smell from air conditioners

Certain components of an air conditioner can exude a bad smell, and can even be enough to odourise your entire space. In order to get rid of this odour, you need to know what is likely causing it and where in the air conditioner the smell is coming from.

So, how can one eliminate an odour from their AC unit?

How to get rid of a bad smell from an air conditioner

Certain parts of an air conditioner can be a breeding ground for an unpleasant smell to develop in. Needless to say, it is difficult to enjoy the comfort of cooling air when the air is filled with a bad smell that, in turn, fills up a space.

To tackle the issue of bad odour coming from your unit, the first thing you can do is flush the drain or condensation line.

Pour distilled vinegar inside the drain line and leave it for 30 minutes, then use a vacuum to suck out any blockage that is likely causing the odour.

Check the drain pan and clean it using vinegar and bleach if it is dirty. You must then wash it with soapy warm water, to effectively remove mould build-up.

Your air filter can also develop mould and debris on it, so you should also clean it too to eliminate existing odour. Finally, to cover all your bases, it is advisable to get a professional to inspect and clean the ductwork of your AC.

Using air purifiers is one alternative to air conditioner smells

Another alternative for addressing a smelly air conditioner is to use an air purifier in the space where your air conditioner is located. Air purifiers are safe to use and effectively remove unpleasant odours from the air.

Purifiers remove odours by cycling the air in the room with the use of a fan. The air is then filtered through an activated charcoal filter that absorbs and eliminates odours.

Since the filter is quite absorbent, it will remove any unpleasant smells from the room by absorbing them completely.

What are the causes of bad odour from an air conditioner?

There are various possible reasons for a smelly air conditioning unit. Mould and mildew are big contributors, as they can develop in the drain lines as well as on the air filters.

It is, therefore, important to clean filters and drain lines regularly to remove any clogging caused by blockages.

Your air filters can collect mould and dirt since they are intended to pull dirt particles out of the air before they make it into the air you inhale. Small bacteria and insects possibly living in your unit can also cause unpleasant odours.

What do certain AC smells indicate?

If your air conditioner smells like rotten eggs or sulphur, this may be an indication that you have a gas leakage in your home that is getting into the air conditioner ductwork.

This is extremely dangerous, as gas leakages can cause fires and even explosions. The smell of dirty socks can be due to standing water or the growth of bacteria in your unit but is not necessarily harmful.

A strong smell of something burning could be an indication of an electrical fire hazard such as a short circuit, motor overheating, or frayed wiring that is sparking.

Air conditioner smells What they likely indicate

Rotten eggs

·   Can indicate a gas leak getting into your ductwork

·   Can be dangerous as gas can explode or cause fire

·   You should turn off the gas supply in your house

Dirty socks

·   An aroma caused by standing water or bacteria growth

·   It is not harmful

·   Change your air filter if it has become wet

·   Call a professional to perform a system clean up and maintenance

Musty mildew

·   Caused by excess dampness in the unit

·   Gets trapped in the ducts leading to growth of mildew and mould

·   Check your filters for moisture blockages and dampness


·   Slight burning scent can form when you turn on the system

·   A stronger burn or gunpowder scent indicates a fire hazard

·   Switch off the system if a strong smell persists and call for help

·   Evacuate your home if necessary, to be safe

Exhaust fumes

·   May indicate a possible leak in refrigerant line or motor

·   Turn off the system completely and get emergency repair

·   Your unit should not smell of exhaust

Vehicle coolant

·   Warns you of a possible freon leak

·   Can be extremely dangerous and toxic if inhaled

·   Switch off the air conditioner and open all windows

·   Call in a refrigerant expert


·   Skunk may have sprayed your outdoor unit

·   The pungent smell can be circulated through your ducts

·   Turn off the air conditioner to stop the spread of the smell

·   Call an HVAC technician to clean the ducts


·   Could indicate that critter has died inside the unit

·   Using the unit spreads the smell throughout the house

·   You need to call in someone to remove the dead animal and clean the duct system

Final thoughts

Often, your air conditioner may have some issues that can seem unusual at first but later make sense when you identify the problem.

Bad odour that exudes from an air conditioner can be something unusual if you have never experienced it, but it will normally point to a more serious problem.

There are varying odours one can pick up from their air conditioner and most of the time they are unpleasant. Smells can be caused by dirty parts of the unit that need to be cleaned or unclogged, but luckily, the odours can be eliminated.

Leave a Comment