If you have a window air conditioner in your home, you might find that it is causing a bad odour. This may only exist when you turn it on or occur any time you enter that room. Here are some steps to follow if you want to remove the smell and end up with a clean and well-maintained air conditioning unit.
Clean or Replace the Air Filter
A good place to start when you have a window air conditioner with a bad smell is to clean or replace the air filter. Since the air filter is there to capture debris and dust, it is often the source of the bad smells. If your air conditioner has a reusable air filter, which many window units have, you will simply need to clean it and put it back into the unit. The air filter should be located behind the front panel of the air conditioner, which opens right up. Some units do require a screwdriver to open the panel. When you have access the filter, pop it out and clean it with mild detergent and cold water. You can use a scrub brush to clean it more thoroughly, but make sure you are gentle and don't cause a tear. Rinse it well and let it dry before putting it back in the air conditioner. If you happen to have a disposable filter, you just need to remove it and replace it with a new one.
Clean the Coils and Fins
You might also have a bad odour in your air conditioning unit simply because it needs to be cleaned. After cleaning the air filter, locate and clean the evaporator coils. These coils might have debris combined with extra moisture that is leading to a mildew smell. The brush attachment on your vacuum cleaner is often the best tool to use for removing dirt and buildup from the coils. If you need to scrub buildup on the coils manually, use a scrub brush made of plastic. You will damage the coils if you try to use a metal scrub brush. After cleaning the coils, check the fins, which are located near the coils in the back of the unit. You can use the same method for cleaning them, though be careful not to bend them.
Find and Fix Water Leaks
Mildew and mould often forms in or around window air conditioners if there is a water leak. You might have a leak and weren't aware of it. If you didn't notice any areas of condensation or moisture inside the unit, that doesn't mean you don't have a leak. You should also check around the unit inside your home, including the window sill where it is installed and on the floor and wall. Also check outside for water that is leaking on the ground underneath the unit. If you find a leak, call an HVAC professional to have it taken care of. This will likely also help get rid of the bad odour.