Why an AC Unit May Smell Like Gas
If severe, a natural gas leak can cause a fire or even an explosion
Air conditioners can occasionally produce strange odors, especially when they are first turned on for the season. Usually, these odors are harmless and the result of dust and other debris in the ductwork. However, a sulfur, rotten egg, or skunk-like odor could indicate a natural gas leak.
What to do when there’s a gas smell
If severe, a natural gas leak can cause a fire or even an explosion. It’s crucial to leave the house immediately. If possible, open a window on the way out so that the gas does not accumulate, then call a utility company or emergency services from outside the home or a neighbor’s house. A utility company representative can shut off the gas supply safely, and once the gas dissipates, a plumber can repair the natural gas leak.
Why the smell comes from the AC unit
In many homes, the air conditioner shares the blower motor, fan, and ductwork with the furnace. If the natural gas supply to the furnace leaks, the air conditioner can draw in the gas through the return ducts and spread it throughout the home. Likewise, air conditioners are often located in basements, attics, or utility rooms near appliances like water heaters and their natural gas piping. Leaks in those systems can also cause the air conditioner to draw in natural gas.
The return ducts should draw air from the living space, not the basement, attic, or utility room. This could be a sign that the air ducts are leaking, and once the gas leak is repaired, it is a good idea to have the air ducts sealed and insulated correctly. According to the Department of Energy, up to 30% of the conditioned air in an HVAC system is lost due to duct leaks, and sealing and insulating the air ducts can improve cooling and heating efficiency by 20% or more.
Other possible causes of a gas smell
In its original state, natural gas is odorless. Suppliers add a methyl mercaptan chemical that produces the signature sulfur or rotten egg-like odor to detect leaks easily. The smell is similar to other common odors, such as skunk spray or the late stages of decomposition. A rotten egg-like odor could also indicate that a rodent, bird, or other animal has been nesting in the air ducts and has since died. In that case, it is a good idea to have the air ducts cleaned and sanitized while repairing any damage the animal has caused.
The scent of natural gas in a home could indicate a life-threatening problem, so immediate evacuation of all people and animals is imperative. Be sure to have the gas shut off immediately and then call a professional to assess the situation. Even if the smell is not dangerous, it’s not worth the risk to hesitate.
Fix My Air DFW of Fort Worth specializes in residential and commercial HVAC services, including routine maintenance, installation, and repair. All makes/models. Call us at (817)839-3511.
