4 Potential Explanations For Your Air Conditioner’s Musty Smell

On a hot and particularly sunny day, your air conditioning system is your best friend. Turning it on after a long and humid day can definitely help you relax and destress. However, things could take a turn for the worse if you suddenly discover that your relaxation time is being marred by a strange, unpleasant mustiness coming from the system!

The good news is that there is usually a logical explanation for a musty smell and you can most likely fix it on your own. To be able to do this successfully, though, you need to start by narrowing down the potential causes. Here are some of the most common reasons for a musty smell coming from your air conditioning system:

1 – The Air Conditioner is the Wrong Size

As a general rule of thumb, you should only use an air conditioner that is the right size for your home. Using an air conditioning system that is either too big or too small will not be effective. If you use a machine that is too small, it may not provide enough cooling for your home and a machine that is too large will cool your home too quickly and not give the machine enough time for moisture control and dehumidification. Either of these things could cause a musty smell.

2 – Poor Filtration System

An effective air conditioner has a good filtration system. The filtration system is in charge of getting rid of contaminants in the air before letting the air out into your home. If your air conditioning system has a faulty filtration system, it will not be able to do its job and as a result of this, it will let out a musty smell. At the very least, check that Furnace Filter.

3 – Dirty Coil

Mold and dust buildup may accumulate on an air conditioner’s coil over time. This will also cause the unwanted smell that comes out of your air conditioner. However, the coil is a more sensitive part of the cooling system. If you suspect that you have a dirty coil, call in an air conditioning technician to come and clean your air conditioner’s coil for you.

4 – Clogged Drains

Dust and dirt may accumulate in the drain pan over time. This will cause the drains to clog and will affect the ability of your air conditioner to dehumidify the air in your home. In turn, this will cause the air to smell musty. Having your drains unclogged by an HVAC professional will help you get rid of the smell and get your air conditioning system working properly again.


Once you have pinpointed the reason behind the musty aroma your air conditioner is emitting, you will be able to actively do something to solve the problem. If you discover that the cause is something that you are not able to handle on your own, calling in an HVAC specialist is always the best solution. Air conditioning systems can be complex, and untrained hands can do more harm than good.

If you need an air conditioning specialist and experts in Edmonton to help get rid of the unwanted smells coming out of your air conditioner, call Legacy Heating and Cooling. We specialize in HVAC systems for residential new home construction (RNC) and installation and replacement of furnaces, air conditioners, air cleaners, thermostats, humidifiers, heat recovery ventilation (HRV) units, humidifiers, and unit heaters, as well as other HVAC products! Get a free quote for your unique problem today!

HVAC Brands We're Proud to Carry

Legacy only uses the most efficient and cost-effective HVAC products. We pride ourselves on putting quality and customers first! We will equip your new home with the best HVAC system and offer the most reliable residential heating service in Edmonton and Calgary.

Contact Us Today

We’ll help you find the right heating and air conditioning system for you and your budget.

Edmonton Area 780-733-1256 Calgary Area 403-451-1337

Honesty, Integrity, Legacy