Why Does My Air Conditioner Smell Bad? How to Fix it?

If there is a mouldy odour coming from your air conditioner, there is a good chance that fungus and mildew have grown near or in your AC. This happens because the air conditioner’s work is removing excess moisture in your home and cooling it too.

When the air cannot properly drain the moisture, mould easily grows in those areas with moisture. Dirty filters can also release the scent of mildew. This is one of the common problems nowadays. The best way to deal with this issue is by calling an AC expert who has experience handling mildew, mould, and fungus. With a technician, the smell will be gone in no time, and the air quality inside your home is going to improve.

AC Smelling Skunk

If the smell is skunk-like, then it could be because of a gas leak. There is a gas known as methyl mercaptan that smells like skunk’s spray. When it gets into the ductwork, your home ends up smelling this way.

This gas is dangerous, and you shouldn’t ignore it because it can put your family at a lot of risks. The moment you smell this, make sure you get everyone outside your home, then contact an HVAC company as soon as possible. They will come to your home and prevent any damage while fixing the problem.

AC smelling like a sewer

It is not a good sign when there is a smell of raw sewage from your AC vent. It could be a sign of a ruptured sewer vent pipe or a backed-up sewer line near the ductwork. Methane is all that is needed to bring that smell inside your home.

Aircon smelling sour

If the AC is releasing a sour smell, it could be a problem with the condensation removal system. When the air conditioner cools the home, condensation is the byproduct. It needs to be properly drained, or else it creates conditions for bacterial and moulds to grow, which ends up with your home smelling foul.

Aircon smelling like vinegar

The condensation from the AC is significant, and if not dried properly, it can turn into mould and mildew. Maybe leaves or natural materials are building up around the AC. When they start decaying, they smell like vinegar. When the AC is turned on, the smell enters your home, which leaves that vinegar smell.

Aircon smelling spoiled & rotten eggs

If you have noticed the smell of spoiled, rotten eggs, then the cause of that smell is a dead animal. Rodents and birds tend to enter the air duct to take shelter, and they can die inside and start decomposing.

When you switch on your AC, the bad odour starts circulating in your home. To deal with such a problem, the technician will have to clean the air ducts to get rid of the animal and the smell.

How do I get rid of the smell in my air conditioner?

Here are 4 simple steps to solve the most common problem of aircon smelling bad.

1. Turning the power to the unit off

When dealing with any electrical system, the first thing you need to do is like an air conditioner is turning off the power at the source. This is important because the last thing you want is to get injured dealing with the AC problem.

2. Changing the air filter

You should make it a habit to change your air filters every 60 days. If your home has a person with allergies or pets, then do it every 30 days. The main work of the air filter is keeping debris and dust out of your AC system. The ancillary effect is keeping the air inside your home cleaner.

3. Cleaning the evaporator coils

When you are done with replacing the filters, use a foaming coil cleaner agent to clean the evaporator coils. They tend to get dirty during HVAC’s normal operation, and it could cause odours. It also reduces the efficiency of the HVAC system.

4. Cleaning the condensate line

There is a drain line near the outside of the unit, and its work is dripping water when the system runs. The condensate line might release sludge or coloured water. Use bleach and water solution to flush it.


If you’re noticing an unusual smell coming from your air conditioning unit, don’t worry. There are a lot of reasons why this might be happening, and we’ll help you figure out what the problem is so it can be fixed quickly! All that’s left for us to do now is ask if our team could help with it?

We’ve helped many people before, like yourself, find solutions or get their AC back on track. What type of smell has been bothering your home lately? Let us know in the comments below, and we will respond right away.

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