10 Common Mistakes to Avoid When Using Your AC

Some of the most common issues with AC units stem from handling mistakes or neglect. In this guide, we break down the most common air conditioner mistakes, plus how to maintain your system properly to avoid costly breakdowns. 

Air conditioner issues don’t just make your home uncomfortable during hot days; they can also affect your health. With poor AC maintenance comes clogged filters, dirty coils, and blocked drain lines. With these conditions come reduced air quality and the perfect environment for mould, dust mites, and bacteria to thrive. 

If you’re not properly taking care of your air conditioning system, you’re setting yourself (and your family) up for: 

• health issues (i.e. breathing problems, allergies), 
• higher energy bills, and 
• expensive repairs or full system replacements.

The good news is, the most common issues with AC units are easily avoidable with the right practices. In this guide, we’ll walk you through the most common AC mistakes homeowners make and how to prevent them from hindering your system’s efficiency and safety. 

Here are the 10 common mistakes to avoid when using your AC: 

1. Forgetting to Replace or Clean the Filter

An AC filter traps dust, dirt, pollen, and other particles so that the air circulating in your AC system remains clean. Air conditioning systems pull in warm air from inside your home, cool it down using the evaporator coil, and then push it back into your rooms.

Before that air gets to the coil, it passes through the filter. 

• If the filter is clean, airflow moves smoothly, and your system can cool your home efficiently. 
• If the filter is clogged, there’s no proper airflow, and your AC system is forced to work harder. 

Can a Dirty Air Filter Stop AC from Working? 

Yes, a dirty air filter can stop your AC from working. When your filter gets clogged, it blocks HVAC airflow. Initially, this simply leads to reduced cooling, but if left unchecked, it can cause the evaporator coil to freeze. Once that happens, your system may shut down entirely. 

How Often Should I Change My AC Filter?

Disposable filters typically need to be replaced every one to three months. However, some air conditioning units use reusable filters that you can clean with water or a vacuum. As a rule, we recommend checking your filter (no matter which kind) every month to stay on top of maintenance.

When in doubt, call in the pros from LG Home Comfort. We offer same-day and next-day service with licensed HVAC technicians who can inspect your system, identify your filter type, and ensure it’s working properly.

How to Clean AC Air Filter 

Do you have a reusable AC filter? Here’s how to clean it:

1. Turn off your air conditioner.
2. Remove the filter (process varies per unit/brand: check your user manual for instructions).
3. Vacuum or brush away the dust. 
4. Rinse with water and let dry completely.
5. Reinstall.

Image Source: Shutterstock

2. Not Cleaning Your AC Coils Regularly 

Your AC has two different types of coils: the evaporator coils inside your home and the condenser coils in the outdoor unit. They’re the main forces behind the system’s cooling process: one absorbs heat from your indoor air, the other releases it outside.

When these coils get covered by dust or debris, your system won’t work properly. Worst-case scenario, you may experience:

• Frozen coils
• Overheating
• Full system shutdown

Any of these common issues with AC units will cost you hundreds to thousands of dollars in repairs or replacements, especially if you ignore them for too long. To prevent this, clean your AC coils at least once a year. 

How Much Does AC Coil Replacement Cost?

Combining both parts and labour, the cost to replace coils in an AC unit typically ranges between $600 and $2,000+. If your unit is older or out of warranty, coil replacement approaches the cost of a new system (portable or window types). That’s why regular cleaning and maintenance are much more cost-effective in the long run.

How to Clean Air Conditioning Coils

1. Shut off your AC unit at the thermostat and the breaker.
2. Access the coils. Evaporator coils are inside (often behind a removable panel). Condenser coils are in the outdoor unit (usually behind a metal grille). 
3. Remove loose debris using a soft brush or cloth.
4. Apply AC coil cleaner following the manufacturer’s instructions. 
5. Rinse, then let everything completely dry. 
6. Inspect for any remaining residue or buildup. 
7. Reassemble and turn back on. 

3. Ignoring Dirty or Blocked Ductwork

Central ACs rely on air conditioner ductwork to move cooled air throughout your home. When these ducts are dirty, blocked, or leaking, your AC won’t provide optimal performance. In most cases, you’re going to experience uneven cooling, higher energy use, and air quality issues. 

To maintain adequate airflow, ensure that:

• None of the vents and registers are blocked by furniture, curtains, or debris. 
• Ducts are free from dust, debris, and mould
• There are no leaks or gaps in the ductwork

How Do I Know if My Air Duct is Blocked?

These are tell-tale signs that your air duct is blocked: 

• Weak airflow from one or more vents
• Uneven cooling across different rooms
• Unusual smells coming from vents (musty, dusty, or stale)
• Excessive dust around vents or on furniture
• Noisy airflow or rattling sounds from the ductwork
• Higher-than-usual energy bills without any change in use patterns

Image Source: Shutterstock

4. Not Checking the Condensation Drain Line 

Air conditioner condensation is a natural byproduct of the cooling process. As your AC removes humidity from indoor air, it produces water that must drain properly. The condensation drain or AC drain line carries this moisture away from your unit.

What Happens If an AC Condensate Drain Is Clogged?

If an AC condensate drain line is clogged, water backs up in your air conditioner. This can lead to issues that are detrimental to your AC and your home, including:

• Water damage (to floors, walls, or ceilings)
• Mould and mildew growth
• Rising humidity levels 
• System shut off due to a triggered safety switch

How to Clean the Drain Line on an Air Conditioner System 

You can clear a minor clog yourself using these simple steps: 

1. Switch off the power.
2. Find your AC drain line. It’s usually made of white PVC pipe, often located near the condenser or evaporator coils. The window AC condensation drain can be found under the exterior part that hangs out of the window.
3. Remove the cap and check for visible blockages.
4. Start your AC cleaning:
   • Use a wet/dry vacuum to remove debris.
   • Flush the line with vinegar or bleach to break down algae, mould, and debris, then flush with water.
5. Reconnect the drain line cap and you’re good as new! 

5. Skipping Seasonal AC Cleaning

Southern Ontario may not be hot year-round, but you’ll want your AC ready when summer hits. Skipping seasonal cleaning of air conditioning systems is one of the most common mistakes homeowners make. 

Don’t assume that the unit stays “fine” when it’s off or not in heavy use. Dust, debris, and wear build up even when your AC isn’t running. Without seasonal AC maintenance, your system may:

• Cool less efficiently
• Struggle to start
• Consume more energy
• Break down when you need it most

Pro tip: Schedule a full system cleaning at least once a year (ideally in the spring) so your unit runs efficiently and reliably all summer long.

6. Pairing AC with Heat-Producing Appliances

Feeling warm even though the AC is set low? Sometimes, it’s not a technical problem. 

If you’re using heat-producing appliances (i.e. stoves, ovens, dryers) during the day, your AC has to work double-time to cool your home. The added heat forces your unit to run longer, use more energy, and wear down faster, especially in smaller or poorly ventilated spaces. 

To help your AC cool more efficiently, try to:

• Run dryers and dishwashers in the evening
• Use exhaust fans to remove heat and humidity
•  Keep heat-emitting electronics away from thermostats

7. DIY Refrigerant Handling

Handling refrigerant, even for a simple AC recharge, is highly dangerous and not recommended for untrained individuals. While you may find DIY tutorials online, working with refrigerant without the proper tools or certification can result in serious health risks, like:

• Chemical burns
• Frostbite
• Breathing problems

Besides, it’s also illegal in Ontario to handle refrigerants without a license. If you accidentally discharge refrigerant into the air, you’re going to have bigger problems than your AC not cooling (read: steep fines and environmental damage).

Image Source: Shutterstock

8. Setting the Thermostat Too Low

Let’s set the record straight: setting your thermostat too low won’t cool your home faster. Your AC works at a constant rate, no matter the setting. Setting it to 18°C (64°F) instead of 24°C (75°F) doesn’t speed things up; it just forces your unit to keep running until it reaches that unnecessarily low temperature. 

That leads to:

• Wasted energy
• Higher electricity bills
• Increased wear and tear
• Risk of frozen coils

Besides, most air conditioners can only cool your room to about 20°F below the outdoor temperature. This means if it’s 32°C (90°F) outside, your AC will struggle to bring your indoor temperature below 22°C (72°F), no matter how low you set the thermostat.

9. Using Wrong HVAC Tools

We always encourage home and business owners to stay proactive in their AC care. Cleaning filters, checking vents, and monitoring airflow are great habits that do wonders for your unit’s lifespan.

However, DIY attempts with non-HVAC-specific tools + wrong handling can do more harm than good (especially for sensitive parts like coils, sensors, or electrical components). Even something as simple as using the wrong cleaner or brush can lead to corrosion, reduced performance, and voided warranties.

To stay on the safe side, it’s best to leave the technical jobs to licensed pros with the right HVAC tools, training, and protective equipment like LG Home Comfort. 

What Is the Most Common Cause of AC Failure?

The most common cause of AC failure is the lack of regular maintenance. Even a simple buildup of dirt in your filter can restrict airflow, overwork your system, and lead to breakdowns. What more if your coils are dirty, your drain line is clogged, or your refrigerant is low?

Routine checks and regular maintenance keep your unit in tip-top shape, preventing small issues from turning into major breakdowns. That leads us to the last item on our list! 

10. Not Scheduling Regular Maintenance 

Most of us are busy with family and work commitments, so it’s not surprising that things like “HVAC condenser cleaning” rarely go on top of to-do lists. However, skipping regular maintenance is a mistake that will cost you.

Think about it, cleaning an AC filter typically only takes 30 minutes or less. The materials you need are items you already have at home; they won’t cost you a buck extra. However, leave it too long, and you could end up with frozen coils, clogged drain lines, poor airflow, or even a full system shutdown.

Any of these problems will set you back a few hundred to several thousand dollars, not to mention the extra cost you’re piling on your utility bills. If you don’t want to deal with common issues with AC units, schedule regular tune-ups and cleaning with trusted HVAC professionals like LG Home Comfort. 

In Summary

Want to keep your AC working efficiently for longer? Avoid these common air conditioner mistakes:

• Don’t forget to clean or replace your air filter.
• Keep your AC coils and condenser unit clean.
• Check your ductwork and condensation drains regularly.
• Don’t ignore strange noises, humidity issues, or poor airflow.
• Avoid DIY repairs, especially if you don’t have access to the right tools or have professional training.
• Schedule professional maintenance at least once a year.

Don’t Let AC Problems Leave You Hot and Bothered This Summer

The most common issues with AC units are easily avoidable, especially with reliable HVAC professionals at your service. LG Home Comfort has been serving Southern Ontario home and business owners since 2017. 

Our certified technicians provide same-day and next-day service with the latest tech and fully equipped vehicles. We arrive fully equipped with industry-grade tools to keep your system in top shape all summer long. 

Let us take care of all your AC needs, be it installation, repair, or maintenance. Call now to schedule your AC service!