When you first turn on your gas central air conditioner, you may be used to the dusky odors that permeate the air the first couple of times it runs while burning off accumulated dust. However, if you notice strange, unfamiliar smells, these could represent a problem. Below are possible causes of three different smells and what may need to be done about them.

Stale, Musty Odor

If your smell a stale, musty odor coming from your air conditioning vents, one possible cause is mold or mildew growth somewhere inside the unit. If so, these need to be taken care of as soon as possible because the growths can cause serious respiratory problems, especially in people who already have breathing problems.

Check the air filter first for signs of growth, especially if it was not changed before starting it for the season. During the winter months, moisture could have become trapped inside the fibers. As the air became warmer, the moist heat can provide the perfect breeding ground. If your filter has visible growth or smells musty, change it and see if it makes a difference.

If you suspect the mold and mildew growth is elsewhere, check the drip pan to the air conditioner. It can be pulled out at the bottom of the unit. If there is old water in it or green growth, remove it completely. Then, soak it in two parts water to one part bleach for two hours. Let it air dry and replace it.

After changing the air filter and soaking the drip pan, it is possible you may still smell the odor. If so, you may have mold or mildew growth inside the compressor or duct work. If you suspect this is the case, you may want to have an HVAC professional inspect it and do any needed air conditioning repair.

Burning Or Smoky Smell

If someone in your home is a regular smoker, it is normal to catch a whiff of a smoky smell as it passes through the unit and ductwork. However, if no one in your house smokes, a burning or smoky smell could be cause for concern.

Open the access panel on your central air conditioner unit, leaving the power on. You will need to have it running so you can detect where the odor is coming from. Just be careful not to put your hands inside the casing.

If you smell the odor while the compressor is running and see a small amount of smoke coming from it or the motor, you may need to have them replaced. This is often a sign that they are about to break down entirely.

However, if you start seeing sparks and detect a burnt, metallic smell, turn off the power immediately. The wiring is most likely faulty and will need to be repaired by a professional.

Strong, Rotten Egg Stench

When you smell a strong, rotten egg stench coming from your gas HVAC unit or your duct work, you could have an emergency situation on your hands. You may have a gas leak in your system.

Because natural gas is odorless, the gas company adds a smell to it that resembles rotten eggs. If you do smell this, open all of your windows and get everyone out of your home.

As soon as you are safely away, call either your gas company or a 24-hour air conditioning repair service to have your home inspected. Do not return home until you receive word that it is safe to do so.

If your air conditioning system continues to emit weird smells or you detect an odor that is not listed above, you may want to contact an HVAC contractor as soon as possible. They can come inspect your unit and may recommend either air conditioning repair or replacement.