Bad odours from your air conditioner are due to a range of factors, including leakages, electrical faults, a build-up of mould, animal infestations and damage to internal components. These are not only unpleasant, they can also cause health issues, including asthma, allergies, skin irritations and respiratory problems. Here is our guide to air conditioner smells, and some tips on how to minimise them.
#1 A stale smell
A mouldy split system air conditioner
If you have a stale or musty smell from an air conditioner, it is typically due to the build-up of mould or mildew. This occurs naturally as air conditioners are dark and humid places that mould and mildew love to inhabit! Air conditioners are designed to remove excess moisture from the air while cooling or heating it, however, if moisture and humidity start to build up, problems can start to occur. Filters, tubes and evaporator coils are significant hotspots for growth. Getting rid of mould in air conditioning systems can also help to minimise health issues, including asthma and other respiratory conditions.
#2 A musty smell
All air conditioners collect moisture as part of their regular operation. When the system is working correctly, moisture is collected in a drip pan and either flows down a drain line or is pumped safely outdoors. If your air conditioner is leaking water, you may start to notice a musty smell, often compared to the smell of dirty socks! Regardless of the cause, the first step is to turn off the unit to prevent further damage to your property.
There are a number of possible reasons your air conditioner is leaking, and most of them will require involving a professional air conditioning technician to solve the problem. One is due to clogged air filters, as they will restrict the airflow passing over the evaporator coils. They can then ice over, and water can start to drip as they thaw. In the process, the heat pump and compressor may be damaged, which can lead to expensive repairs.
Some units have a condensation pump to push water collected outside. If this is damaged in any way, the water will have no way to escape, it will build up and the system will start to leak. In this case, the pump will need to be repaired or replaced.
Another common reason an air conditioner may start to drip water is because of a clogged drain line. Debris and dust can collect and eventually clog the drain hole, and once the pan is full, the water will start to drip over the sides.
If an air conditioning unit is low on refrigerant, its coils can begin to freeze over. Each time the unit shuts off, the ice will melt, and it can start to overflow the drip pan.
Units that aren’t installed correctly can also lead to leakage over time. This is particularly the case with the P-trap and vent line that are designed to prevent water from being drawn back into the drip pan when airflow causes negative pressure. In addition, if ductwork wasn’t properly sealed and insulated when it was installed, moist ambient air will start to be drawn into the system. Once mixed with the cooler air in your unit’s ducts, condensation can form, and leakage may develop.
#3 A burning smell
Air conditioners have their fair share of circuitry and components. And like all electrical appliances, faults can occur. Burning or “gun powder” odours typically mean functional problems with electrical wires, fans or motors, caused by overheating, water damage, a build-up of dust, or the circuit may be receiving the incorrect voltage. Over time, electrical components can also wear out, causing mechanical failures and lead to short circuits. If you notice burning odours or even worse, smoke, shut down the unit immediately and contact your air conditioning technician as soon as possible.
#4 An exhaust smell
Air conditioners have motors, and motors require lubrication in the form of oils. If you have a smelly air conditioner and the smell is more like exhaust fumes, it could be due to an oil leak or the central unit overheating, which can cause oils to burn. Exhaust aromas are not only unpleasant, they can also affect indoor air quality and lead to health problems.
#5 A rotten egg smell
The smell of rotten eggs shares many similarities to natural gas. So if you are detecting this odour, your air conditioner may have a gas leak. Gas leaks can lead to carbon monoxide poisoning, which can be extremely dangerous. You should open windows immediately to ventilate the area, shut the unit down, and disconnect your home’s gas at the mains as a precaution. Then, call your technician ASAP!
#6 A chemical smell
If your air conditioner is emitting a chemical-like smell similar to chloroform or paint thinner, it may signify your unit is leaking essential fluids. Refrigerant gas in reverse-cycle air conditioners treats the air before it is dispersed throughout your home. A chemical smell suggests that the refrigerant is leaking, which can limit your system’s performance as well as be hazardous to your health.
#7 A methane smell
Dead animals can give off a methane smell
If your air con smells like methane or has a sulfuric odour, it can indicate an animal (like a mouse, rat, bird or possum) has taken shelter in your air conditioning system’s ducts and has died. This is particularly the case during winter when animals are seeking a warmer place to nest. However, dead animals not only cause foul odours. They can also chew through and damage ducts, wiring and components.
#8 A cigarette smell
The coil and air filters can absorb cigarette smoke and release it later. If you don’t smoke, there can be a chance that the previous tenants/owners were smokers and the unit is releasing old smoke. You should contact your technician for a thorough cleaning of the unit and an air filter replacement to get rid of the smoke odour. If you do smoke, avoid smoking indoors to prevent this from happening again.
How to get rid of a bad smell from an air conditioner
If you’re wondering how to stop air conditioner smells, the most obvious answer is to regularly maintain your unit. Some maintenance you can do yourself, including cleaning the filters, louvres and the outdoor unit. You should check your unit’s instruction manual for details, but typically this is a relatively simple process.
Clean filters
Manufacturers usually recommend that you clean the dust filters every few weeks, but it really depends how often you use your air conditioner — the more you use it, the more often you should clean the filters.
Take the dust filters outside for a good brush or shake. They can usually also be vacuumed for a thorough clean – use the vacuum cleaner’s brush head if you have one.
If the dust filters are very dirty, you can wash them in warm water with some mild detergent and rinse them clean. Make sure they are completely dry before putting them back into the unit.
Clean louvres
You may also be able to remove the indoor unit’s louvres (the oscillating blades that direct the airflow). Give them, and the space behind them inside the unit, a thorough clean with a dry cloth or with the vacuum cleaner. Again, make sure the air conditioner unit is turned off before you do this.
Cleaning your outdoor unit
Keep the outdoor compressor unit clear of surrounding grass and plants, and brush away dust, leaves and cobwebs regularly. Running a vacuum cleaner over the air intake can help clear dust from inside. We don’t recommend that you open up the unit to clean its internal components – leave that to a professional service.
In terms of timings for DIY maintenance, if you use your air conditioner regularly, it is also recommended you run the unit in fan-only mode every month to evaporate any moisture inside the indoor unit, which helps prevent mould and odours.
Regular professional servicing
Although some maintenance can be done yourself, other servicing should be done by a licensed air conditioning technician. Regular servicing will keep your unit running efficiently, ensure indoor air quality and address any issues (including bad odours) before they become more significant problems. Typically, during a service they will:
- Check that the heating and cooling functions are working.
- Check the airflow.
- Clean the evaporator and condenser coils.
- Check the gas and refrigerant levels.
- Check and tighten electrical connections.
- Check the outdoor unit and that the fan is operational.
- Flush the drains.
- Check, clean and repair the ductwork if needed.
Noticing a strange smell from your air conditioner? Time for a service! Contact Crown Power today on 0427 175 654 (Brisbane & Sunshine Coast) or on 0409 678 803 (Gold Coast).
