air conditioner smells

7 Insidious Air Conditioning Smells and their Surprising Causes

There’s nothing quite like an unpleasant odour to ruin your day. A foul smell produced by an air conditioner could be a sign of a severe problem and potentially a hazardous situation. So if you turn on the air con and a bad smell emanates from the vents, then you’re going to need to request maintenance.

Bad air conditioning smells are nothing to be scoffed at. It is possible that your air filter just needs cleaning. But it’s also possible that the circuits are fried, and a potential fire hazard is heating and cooling your home. So AC smells should be investigated right away.

Here are 7 of the most common air conditioning smells and their causes:

air conditioning smells like mould

1. Mildew or Mould Air Conditioner Smells

If your air conditioner emits a stale or musty aroma around the house, it could result from a leak somewhere in the system. It’s not uncommon for the drip lines, drain pan or evaporator coil to clog and then leak. This leaking water can pool and become a suitable breeding ground for mildew or mould. Mildew and mould are two of the more common causes of bad smells.

Alternatively, a musty aroma can be caused by a dirty air filter, particularly in regions with high humidity. The additional moisture can settle on the filters and produce unpleasant smells, and dirty filters can also affect air quality. So we recommend that you clean the filters every three months by brushing the dust off and washing them in soapy water. Anyone can clean a dirty filter. However, you will need the assistance of an expert to fix a leak.

burning smell from air conditioner

2. Air Conditioner Smells Like Burning

Air conditioning carries its fair share of components and circuitry. And like all electrical appliances, there’s room for faults. A burning odour will likely indicate that one or more of the electrical components are burning. This can be caused by water damage, overheating, a build-up of dust and many other issues.

If the smell dissipates quickly, then there may be nothing to worry about. But if the smell sticks around for longer than a few seconds or the unit produces smoke, you should shut it down immediately and call an HVAC technician before further use. Booking a scheduled service can limit the chance of build-up and clogs, so it’s always wise to organise an annual service.

air conditioning smells like eggs

3. AC Smells Like Rotten Eggs

The rotten eggs smell shares many similarities with natural gas, so if you’re smelling eggs, then there’s a good chance that the air conditioning smells are caused by a gas leak. The gas itself has no odour, so the distinct smell is added as a safety precaution.

As a gas leak can lead to carbon monoxide poisoning, you must act immediately if your air con or any appliances, for that matter, give off a rotten egg smell. First, open windows to ventilate the area. Then, shut the air conditioner down and consider closing off your home’s gas connection at the mains if the problem is not limited to the air con. Then you will need to call a licensed gas fitter or air con professional for a repair before it’s safe to use the system again.

air con chemical smell

4. Air Conditioning Produces a Chemical Smell

An air conditioner emitting a chemical-like smell, something reminiscent of paint thinner or chloroform, can signify that your system is leaking essential fluids. Refrigerant gas is present in reverse cycle air conditioning and is relied upon to treat the air before it’s dispersed throughout your home. A chemical odour suggests that the refrigerant is leaking, which can be harmful to your health and the environment while also limiting the performance of your air con.

Only licensed air conditioning technicians are legally permitted to perform an air con regas. So shut down your AC if you smell chemicals, crack the windows and give us a call.

air conditioning smells like exhaust

5. AC Smells like Exhaust Fumes

No natural gas supply? That won’t stop an air conditioner from producing a smell similar to a car’s exhaust fumes.

Air conditioners have motors. Motors require lubrication. And so oils come into play. If the oil were to leak or the central unit was to overheat, it’s possible for that oil to burn and for those undesirable exhaust aromas to affect the indoor air quality.
The exhaust can be hazardous to your health if not ventilated properly. So contact your HVAC system professional and get that issue fixed.

gunpowder smell

6. Gunpowder Air Conditioner Smell

An air conditioning unit emitting a gunpowder smell can signify a serious problem. It’s likely that the fan motor or circuit board is fried and needs replacing. This can be caused by overheating, water damage or the circuits receiving the incorrect voltage.
The smell of fried electronics is not dissimilar to the fire-like smells mentioned above.

However, the damage here can be much worse. Once again, the fumes can cause respiratory problems. It’s advised that you shut down the AC right unit away and crack the windows before calling for repairs.

air conditioning sulphur smell

7. AC Produces Sulphur Smell

We saved the ‘best’ for last. If you’re trying to enjoy the comfort provided by an air con only to be struck by a methane or sulfuric odour, then there’s a good chance that an animal or rodent has died in your system.

Critters like rats, mice, lizards, birds and possums have all been known to explore the insides of a compressor or ducts only to get trapped within and die. It’s only a matter of days before they start to produce a distinct smell that you can’t mistake for anything else. The good news is that our technicians can address this problem and investigate if the system’s performance has been affected.

Air Conditioner Repairs

If you’re experiencing any of the above air conditioning smells, your best course of action is to have a professional inspect the HVAC system and recommend the appropriate fix. Repairs or a thorough clean will hopefully be all that’s required. But if key circuitry has burned out, it might be time to consider replacing the air conditioning system or looking into an upgrade.

Whatever the cause, give Metropolitan Air Conditioning a call, and we can schedule an inspection or provide emergency after hours service. Request a repair and improve your indoor air quality today!

Published: 29 Apr, 2021

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