Common Causes of a Stinky AC and What To Do About It

If you’re having your home’s heating and cooling system serviced regularly (ideally, twice per year — once in the spring before cooling season and once in the winter before heating season) then most typical HVAC issues will never crop up in your system. That’s because your heating and cooling company will spot early signs and nip issues in the bud before you even notice they’ve begun.

But even well maintained systems can occasionally have an issue between service appointments. If your heating or cooling system has started to stink a bit, and you’re wondering if it’s a major problem or if it can wait until your next routine appointment, we can help.

My AC Smells Like Dirty Socks

If this has happened to your air conditioning system in the summer, you know it isn’t pleasant. You’re left wondering if you have to live with your house smelling gross just to be able to get some relief from the outdoor heat. This is a common problem, and the good news is that, caught early, it’s quick and inexpensive to fix. Air conditioning doesn’t just cool your home’s interior air, it also pulls moisture out of the air, reducing the indoor humidity and making the air feel even cooler. Ideally, the humidity that’s removed from your air by your AC system is collected and drained without you even knowing it’s happening. Sometimes, though, the moisture collects somewhere it can’t drain, or the drain lines become blocked. Either way, mold and mildew can form in your drain line or around your HVAC equipment, creating the stinky “dirty sock” smell.

Mold? Oh No! What Do I Do?

This isn’t a cause for panic, but it shouldn’t be ignored, either. First, if you can smell the stink, it means the mold and mildew are probably being blown throughout your home as the AC distributes the cool air. This isn’t great for anyone’s health and breathing, and it also spreads mold spores that could get deposited in other damp areas of your home, allowing the mold to flourish. Removing mold and mildew from your AC drain line is a quick and easy fix — removing it from your basement, behind your walls, or from your attic insulation is a whole other matter, so you want to get rid of the mold or mildew at its source, before it can get a foothold elsewhere.

Secondly, a small amount of mold or mildew in your AC drain line is not problem to remove and clean up. If that moldy water overflows its current location (which is not unlikely if the drain line is blocked) it could spread in the area around the air conditioning unit, taking hold behind your walls or in your floors or ceiling, where it can spread, unnoticed. So although smelling a “stinky sock” smell in your air conditioning isn’t a reason to move out or panic, it’s not something you want to put off dealing with. Especially because it really is a quick and easy fix.

The Vanishing Smell (But It Isn’t a Vanishing Problem)

One note — if you’re located here in Cincinnati, it’s likely that if you don’t deal with your moldy AC, the smell will go away when you switch to heat in the winter. This is because heated indoor air tends to be drier than cooled air. (This isn’t true in places like Florida, where the air is humid year-round.) The drain lines for your AC won’t be needed in the winter, the moisture will dry up, and the mold will (more or less) go away. But the problem isn’t solved! The next time you turn your AC on, the drain line will still be blocked, the moisture will collect again, and the mold will come back. If you’re lucky, this will only mean a repeated cycle of smelly summer AC. But if the mold survives and spreads each year, even just a little, you can get a serious mold problem over time that can wreak extensive damage on your home and rack up huge repair bills. All for a little, blocked drain line!

If you’re on a regular schedule with your local HVAC company, you should definitely mention your stinky AC to your heating and cooling technician the next time they come out for a maintenance appointment. But if you’re more than a few weeks away from your next appointment, call and ask your tech to come out for an additional appointment. This is SUCH an easy problem to solve, if it’s dealt with early. It’s well worth the cost of an extra AC service visit to protect the health of your family and the safety of your home. If you’re here in the Cincinnati area, our AC technicians here at Jansen Heating & Cooling are happy to come out and clear your drain line, solving the problem and getting rid of the stinky sock AC.