The Most Common Air Conditioning Failures (And How To Repair Them)

The air conditioner is a masterpiece of technological ingenuity that tames inclement weather conditions. Until it doesn’t. Air conditioning systems, regardless of the type, have their own set of unique and, often unexpected, problems. And since the majority of American households have at least one air conditioner unit installed, chances are you have experienced failures firsthand. This is especially frustrating if it happens at the peak of summer when you need the cooling breezes the most.

Air conditioning failures come in all forms and degrees of severity. Some, including dirty air filters, drainage problems, and a freezing condenser coil, can be easy to fix without having to look for a technician. But others, such as a damaged compressor and capacitor failure, would call for a professional to handle them. These usually imply that one or more parts of the unit are malfunctioning and should be replaced. Between those two extremes, other problems of mild severity might pop up. Then, you can either put on your technician hat and try to fix it yourself or take the costlier, yet easier, route of calling an expert. Read more to find out the most common air conditioning failures and how to fix them.

The thermostat isn’t functioning correctly

After setting the thermostat to the ideal temperature, you usually have to wait for the mandatory first few minutes before the gentle, cool air flows in. But when that doesn’t happen and the air in the room continues to be warm, humid, and sluggish, then something is off. You check the AC unit only to find out that the air it blows out is slightly cool at best, or balmy at worst. The air conditioner is not playing tricks on you. You may just have a malfunctioning thermostat.

Thermostat malfunctioning is a more common air conditioning failure than many people think. It can have a simple reason behind it, such as the batteries are dead and need to be replaced. But other more sinister causes could lead to thermostat damage. These include broken wires, corrosion, loose screws, or simply dirt build-up. If the thermostat uses batteries, that’s the first thing to check. Replace them and see if that fixes the problem. Otherwise, you might have to call a professional to sort out the issue or replace the thermostat altogether.

Water is leaking from the unit

It’s not normal for water to leak out of the air conditioner either indoors or outdoors. But as you might expect, such mishaps can happen for a wide variety of reasons. If the water leakage is indoors, then the condensate drain pipe, where the moisture inside the AC unit safely drains out in the pan, might be clogged. Fungal build-ups that thrive in humid conditions are often the culprit behind the clogging. Switch off the air conditioner then use the manual to locate the condensate drain pipe. Mix equal amounts of vinegar and water or bleach and water and pour the liquid inside the drain pipe to kill the fungi and unclog it. However, if the drain pipe isn’t clogged, then the condensate pump might be malfunctioning, and you’d need to have it replaced.

If the water is leaking from the compressor outside, then the issue could be damaged condensate pans, poor installation of the unit, or the seal has gone bad. Unfortunately, none of these problems should be fixed by consulting the manual and watching a YouTube video. You should turn off the AC unit and give the technician a call.

The air conditioner is making noises

Air conditioners and noise don’t, or at least, shouldn’t, mix. No matter what type of air conditioner you have, a quality, well-functioning one should purr like a kitten. When loud noises come out of the AC after you turn it on, you may have a serious issue on your hands. These noises, when they happen, come in different tunes and pitches. A faint bubbling noise tells you that there may be a refrigerant leak, or that the unit has a lot of moisture build-up. A persistent clicking sound means that the capacitor may be malfunctioning, or the fan has debris and grime build-up. Meanwhile, a loud grinding sound is an omen that either the motor or the compressor is about to fail.

These noises can be serious warning signs. And you shouldn’t trust your ear to distinguish between a faint bubbling noise and persistent clicking, let alone diagnose the cause of the failure. As with other serious issues regarding the air conditioning system, a professional should handle this one. They can determine the source and type of the noise and the best fix for such an issue.

The air filter is clogged
The AC air filter has one job to do: screen the airflow for specks of dust, lint, pet hair, and dead bugs and keep them from cycling through the house. Over time, the filter mesh can become clogged with these pollutants. It’s a slow and steady process, but its impact is decisive. The airflow increasingly diminishes, and the AC takes longer to cool down your home. This, in turn, has other undesirable effects, including but not limited to a spike in the electricity bill, frozen evaporator coils, and acceleration of the wear and tear of the air conditioning unit.

Air conditioner filters come in two types: replaceable or reusable. Replaceable options can only be used once and you should replace these air filters every one to two months depending on the quality of the air in your home and whether anyone has allergies. But if you have a reusable air filter, sometimes called a washable air filter, you should clean it every few months. Switch off the AC and open the front panel to remove the air filter. Wash it with a mixture of warm water and detergent, then rinse it thoroughly.

The capacitor is failing

Sometimes the air conditioning system seems to be working. The condenser is humming, and the fan is whirring as it should, but the temperature indoors isn’t decreasing. When the AC is running but fails to regulate the temperature, it’s time to investigate the capacitor. These come in two varieties: start capacitors and run capacitors. A failing start capacitor doesn’t provide the surge in power necessary to get the system running, while a bad run capacitor switches off the unit in the middle of a cooling cycle. The reasons for such failures vary but can be summed up as normal wear and tear, exposure to a heat source, and frequent power spikes.

AC capacitors are built to last and you can get around 20 years of service out of them, provided that they’re not exposed to the sun or power surges. But when they fail, they could blow up and bring about damage to the other components. Call a technician and have them test the capacitor with a multimeter to determine if it’s broken, in which case, it should be replaced.

The air conditioner refrigerant is leaking

Leaking refrigerant, aka freon, is just as deceptive as a bad capacitor. In both cases, the compressor and the fan motor are working just fine, but the temperature indoors doesn’t meet the thermostat setting. However, in the case of the leaking refrigerant, there’s a serious health risk involved since the chemical is highly toxic. Some telltale signs that the AC refrigerant is leaking include frozen evaporator coils, dwindling cooling performance, and a hissing or gurgling sound coming out of the condenser.

Freon can leak from the AC unit due to shoddy installation or corrosion of the copper tubes, either because of friction or exposure to acidic chemicals. The system is also more likely to spring a leak if it’s an old model where wear and tear has undermined the integrity of its components. Whatever the source, a leaking refrigerant is a serious system failure and you shouldn’t try to fix it yourself. Stay away from the leaking AC to limit your exposure to the chemical and call a professional to handle it safely.

A persistent burning smell coming out of the vents is cause for alarm. It usually indicates that the components of the unit are overheating and could soon fail. Calling a technician is the right course of action here. On the other hand, a rotten smell wafting through the open vents is usually nothing more than a dead rodent that’s found its way inside the ducts and will need to be removed. But the same cannot be said about a chemical- or nail polish-like smell oozing out. This is a sign of a Freon leak. Switch off the AC and call a technician immediately.

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