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Why Does The Air From My Air Conditioning Smell Bad? A Phoenix Tech Explains.

2016 Oct 26

If you’ve noticed that your air conditioner is putting out some gross odors every time it kicks on, you’re probably wondering if that’s normal.

Well, different AC smells mean different things.

Two of the more common AC smells (and their causes) include:

  • A musty or “dirty sock” smell, which is usually caused by mold, mildew and bacteria buildup inside the system
  • A rotten egg smell, which usually means you have a pest problem or a dead animal in your AC system

If you smell either of those smells from your AC contact us for a check-up, save time and money book online and get a Heating or AC Maintenance Check-up coupon only pay 29.95!

Because we obviously aren’t in your home to diagnose the problem, we’ll show you how to identify the problem you’re dealing with and what you can do to get rid of the smell.

If your AC smells like mildew or “dirty socks”... likely have one of these problems:

  • Mold on your evaporator coils
  • Mold in your ductwork
  • A clogged condensate line

Let us explain these in more detail and how to fix them.

1. Mildew/mold on evaporator coils 

So, how and why does mold and mildew grow on your evaporator coils?

Well, as warm air passes over those cold coils, condensation occurs. And if there’s any dirt or dust present, that provides the perfect breeding grounds for mildew, mold and other bacteria. 

Signs of a dirty evaporator coil:

  • Visible signs of bacteria or mold/mildew buildup on your evaporator coils
  • Ice forming on coils
  • Weaker air flow than normal

What to do: Have a professional clean your evaporator coil. Usually, this requires some disassembly so we don’t suggest trying to clean this on your own.

2. Mold in ductwork

If you have mold growing inside your ductwork, it could have been caused by:

  • Leaks in the air ducts (see “How Can I Tell If My Air Ducts Are Leaking?”)
  • High indoor humidity levels
  • Mold growth that’s spread from another source

Signs of moldy ducts:

The only way you can be 100% sure that you have mold growing in your air ducts is by visually inspecting your ducts. 

Now, we know that getting an up-close look at the insides of your air ducts is a little tough for the average-sized person. Which leads us to our next point...

What to do: Have a professional inspect your ductwork. They’ll be able to inspect areas that you can’t using special inspection cameras. 

But beware professionals who insist that you need duct cleaning only. Simply cleaning your ducts won’t permanently solve the problem. Instead, they should be looking for what caused the mold growth in the first place.

3. Clogged condensate drain line

Your condensate drain line is designed to catch and drain away condensation that drips off your evaporator coils. But if this system gets clogged, the standing water that’s trapped can quickly lead to mold and bacteria growth.

Signs of a clogged condensate drain:

  • Water leaking around the indoor unit
  • Your AC shuts off suddenly (some units have a safety switch that shuts off your AC if the drain pan overflows)

What to do: The good news is that we have some easy-to-follow instructions to unclogging the condensate drain line yourself

But if you’d rather not deal with the mess yourself, just have a professional unclog the line for you.

If your AC smells like rotten eggs… probably have a pest problem or dead animal in your air ducts or your attic.

We know. It’s not pretty to think about, but it happens.

Signs that you have a dead animal in your air ducts:

  • The smell is stronger the closer you get to the vents.
  • You’ve heard “scurrying” pests prior to the smell.
  • You find pest droppings, hair, etc. inside ducts.

What to do: Have a pest control professional locate and remove the animal. 

Not sure what’s causing your AC to stink? Ask a Phoenix tech!

If you’re having trouble pinpointing the nasty smell coming from your AC, we’re here to help.

Just schedule your appointment today, and we’ll send an HVAC tech over to find and fix the problem.

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