Few things strike more fear in the hearts of South Floridians than a broken air conditioner in summer. Once it fails you’re in for some brutal, if not dangerous, heat, and you’re at the mercy of the technician’s schedule, not to mention the repair costs.
How do you keep your AC from breaking down? Should you pour bleach down the overflow pipe? Can you vacuum the slime out? Do you really need high-end filters?
We spoke to local AC experts about how to avoid those dreaded AC failures.
Filter fix
Adam Ross, executive director at the South Florida Academy of Air Conditioning in Fort Lauderdale, which trains HVAC students, said changing your filter is one of the easiest ways to keep breakdowns few and far between.
“You want to change your filters every month,” he said. “It’s better to buy a less expensive air filter and change it every month than it is to buy an expensive air filter and only change it every six months.”
Filters can cost between $12 and $80, which can create misunderstandings when shopping. “People think, ‘Oh, I’ll get a better one and it’ll last longer,’ ” Ross said. “It doesn’t work like that. It’s better to get a less expensive filter and commit to changing it.”
Marco Stangoni of AA American Air Conditioning of Delray Beach, agrees. “The filters are the one thing you always want to keep up on,” he said. “I would get the least expensive paper filters. You’re going to have to change them a little more frequently, so buy a case at a time.”
He added that the proper size is important. “If you don’t get the right size filter, all the dirt’s going to bypass the filter and ruin your coil, and you’ll end up with big expenses later on.”
Ross said if you don’t change filters often enough, it stresses the system. “When the filter starts to accumulate dust and debris, you’re not going to get as much air flow in the system and it will make your system work harder, which can lead to failures faster, especially if you have an older system.”
Stangoni suggested changing filters every month or two months, depending on how often you open your door or whether you have pets.
Clogged culprit
Clogged drain lines might be the most common cause of AC failure. “They’re one of the biggest culprits,” Ross said. “and they can happen to new or old systems.”
Ross explained that clogging occurs because AC units not only cool, they dehumidify. The system collects that moisture in a pan and sends it down a pipe to the exterior of the house. When that pipe clogs with accumulated algae and slime, the pan fills up and can spill over, flooding whatever space the AC is in, often an attic or closet. To prevent this, units have kill switches that shut the AC down when the pan fills up.
That’s when a lot of people call an AC tech. But there are ways to prevent slime buildup, and ways to unclog a pipe without an AC tech coming over.
To prevent the pipe from clogging, some people pour bleach into the top of the pipe every month or two. The top of the pipe is always at the interior unit and accessible. Other homeowners use tablets. Opinions differ on the use of bleach – some say it’s fine, others say it’s corrosive to PVC pipes.
“Old school folks do put bleach,” Stangoni said. “We’ve used vinegar. The vinegar doesn’t seem to have the same potency. I don’t personally put bleach in my line because I don’t know what effect that’s going to have on the glue that holds the [PVC] fittings together.”
“Don’t pour bleach down the drain line,” Ross said. “It won’t help your problem over the long term.”
He said you can buy anti-slime tablets online that have a slow release. “That’ll kill slime and sludge over time,” he said. “It’s not the end of the world if you pour bleach down there.” But he said the slime is going to start to grow back. The tablets offer longer-term prevention.
“Tablets are OK,” Stangoni said. But if the line is already full of algae they’re not going to get rid of it. In other words, he sees them as preventative but not a solution if the drain pipe is full of slime.
As for bleach’s corrosiveness on PVC, an online retailer for industrial supplies and PVC, pvcfittingsonline.com, says, “You can safely use bleach to clean and disinfect your PVC pipes, as long as you dilute it first and avoid mixing it with other chemicals.”
The site suggests a dilution strength of one part bleach to four parts water for regular cleaning and disinfecting, and a one-to-two ratio if necessary.
Be careful not to mix the chemicals you pour down the pipe, though. Mixing bleach with ammonia or vinegar “can create poisonous gasses that can cause damage to your piping and your health,” says pvcfittingsonline.com.
If the pipe is already clogged, there are some easy at-home solutions you can try before calling a technician. Typically, a tech will blow the drain out with compressed air. But you can use a vacuum to suck it out the other end.
Stangoni suggests using a vacuum both preventatively and as a fix after a clog. He said it’s a good idea to vacuum out the line every few months. “That’s something any homeowner can do,” he said.
You’ll need a small wet/dry vacuum that you can pick up at a hardware store. He said the PVC is typically ¾-inch pipe, and the wet/dry vacuums have tubing that should fit tight upon the outflow pipe.
First, turn off your AC. Then snug the vacuum’s nozzle on the AC’s outlet pipe outside the house, and let the vacuum run. While it’s running, go inside and listen at the other end of the pipe. “Make sure you can hear the vac pulling at the other end,” he said. “You need to hear that vac sound coming from the outside to the inside, so you know it’s clear.”
Refrigerant failures
Refrigerant fluid, or lack of it, is another culprit. If the air coming through the ducts doesn’t seem that cold, there could be a refrigerant leak, Ross said. He said that copper lines can start to leak refrigerant in systems that are older than 10 years.
Refrigerants, such as Freon, are clear and difficult to see. “You can spray soapy water on the evaporator coil and look for bubbles,” said Ross, “but you probably want a service tech out there to do that.”
If there’s one leak, there’s usually more, he said. Refilling Freon is the cheaper option, but it doesn’t fix the leak. “It’s also bad for the environment,” Ross said.
The other option is to replace the entire system. That’s obviously much more expensive, but Ross said it might save you money in the long run.
Dusty ducts
The ducts that bring air to each room can get quite dusty, and some marketing materials for duct cleaning services warn of mold. But Ross said “there’s not a ton of efficiency loss, even if they’re dusty.” He said cleaning them is more about hygiene.
Stangoni is a little more duct-averse. “I would leave ducts alone unless they’re dirty from construction,” he said.
The outside unit
The outside AC is less complicated, and blows hot air away from the house. But it still needs a little attention.
“Everything is about airflow,” Ross said. “The unit outside needs airflow. It’s pulling heat from inside your house, and blowing it outside, and sucking air through the sides and blowing the air up. So you need some clearance around the side. It’s common in Florida that people want to hide them, so they pack in hedges around it.” Those hedges can grow in, so make sure there’s a bit of space for airflow.
The outside unit also contains steel coils. “I would not mess with the coils at all,” Stangoni said. “I would leave the [coils] on the outdoor unit alone … You can’t constantly pour water on them because they’re metal, and it will degrade the metal.” There’s one exception, though, he said. Houses often have dryer vents placed near the outdoor AC unit. “That lint can start to accumulate inside the coils. So you gotta watch out for that.”
Bill Kearney covers the environment, the outdoors and tropical weather. He can be reached at bkearney@sunsentinel.com. Follow him on Instagram @billkearney or on X @billkearney6.
