Proper maintenance and usage of a wall-mounted air conditioner are essential to ensure optimal performance, increased durability, and reduced energy costs. Yet, even with good intentions, many homeowners in Montréal, Laval, Longueuil, as well as on the North Shore and South Shore, make mistakes that seriously compromise the efficiency of their unit. At AirGreen, with our extensive experience in installing and servicing wall-mounted air conditioners, we’ve identified the most common errors we correct on a daily basis. This article breaks down the five most common mistakes to avoid at all costs – and how we help our customers get the most out of their wall-mounted air conditioning system.
Improper installation from the start
A poorly installed wall-mounted air conditioner is destined to underperform—or worse, break down prematurely.
Common installation mistakes:
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Poor placement of the indoor unit: too close to the ceiling, blocked by furniture, or facing an unused area.
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Improper insulation or sealing of the wall penetration for the refrigerant piping, leading to energy loss.
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Faulty drainage design, resulting in water leaks and humidity issues.
At AirGreen, our certified technicians ensure every wall-mounted air conditioner installation meets strict criteria for tilt, accessibility, insulation, drainage, and electrical compatibility. A bad installation often stems from inexperience or attempts to save money in the short term, which ends up costing much more in the long run.
Skipping regular maintenance of the wall-mounted air conditioner
Neglected HVAC maintenance is one of the main causes of lost energy efficiency.
Consequences of poor maintenance:
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Clogged filters reducing airflow and forcing the unit to overconsume.
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Dust and mold build-up on the coils.
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Miscalibrated temperature sensors causing irregular performance.
We recommend at least one professional maintenance visit per year, ideally in spring. During these visits, our team cleans the filters, checks the drain, measures pressures, and assesses overall performance of the system. In the Montréal region, where summers are increasingly hot and humid, skipping these steps can compromise your comfort for the entire season.
Installing an underpowered or overpowered unit
It’s common to choose a unit that’s either too small or too large for the space it needs to cool.
Consequences of poor sizing:
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An underpowered unit will constantly run at full capacity, wear out faster, and fail to cool effectively.
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An overpowered unit will start and stop frequently, reducing its lifespan and causing uncomfortable temperature fluctuations.
At AirGreen, we always conduct a precise heat load evaluation, considering square footage, insulation, sun exposure, and number of occupants. For example, in a recent installation in Laval, we replaced an old 9,000 BTU underpowered air conditioner with a Gree Lomo 12,000 BTU model perfectly matched to the space, which immediately improved comfort and reduced energy consumption by 18%.
Misusing the remote control
A simple yet frequent mistake is using the wrong settings or leaving the unit on Auto mode all season without any adjustments.
Common misuse habits:
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Always using “High” mode, thinking it cools faster (when it mostly just consumes more power).
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Not activating “Sleep” mode at night, leading to discomfort or overcooling.
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Not using the timer, resulting in unnecessary operation while away.
Our technicians always take the time to explain the optimal settings, especially modes like “Eco,” “Dehumidification,” or “Fan only.” In a recent installation of a Fujitsu KZ wall-mounted air conditioner on the South Shore, our client was surprised to learn how effectively the “Dry” mode reduced humidity during the day without drastically lowering the temperature.
Ignoring early warning signs
A wall-mounted air conditioner often gives early warning signs: unusual noises, loss of power, strange smells, or frost buildup.
The most costly mistakes:
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Ignoring water dripping under the indoor unit.
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Continuing to use a unit that frequently ices up.
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Delaying a service call when hearing metallic noises or vibrations.
We encourage all our customers across Montréal, North Shore, and South Shore to call us at the first sign of abnormal behavior. In a recent service call in Longueuil, we were contacted about a small vibration noise that turned out to be the early stages of compressor failure. Thanks to a quick response, we avoided a complete unit replacement.
Best practices to avoid these mistakes
Here are some simple yet essential tips to optimize the performance of your wall-mounted air conditioner:
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Have the system inspected and cleaned at least once a year.
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Choose a qualified HVAC installer like AirGreen.
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Make sure the unit is properly sized for your living space.
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Understand how to use your air conditioner’s features.
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Act quickly when you notice a problem or unusual behavior.
Why choose AirGreen for your wall-mounted air conditioner needs?
At AirGreen, our HVAC expertise is backed by hundreds of successful installations across Montréal, Laval, Longueuil, the North Shore, and the South Shore. Our clients appreciate:
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Personalized advice tailored to their budget and space.
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Meticulous installation that meets all regulations.
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Reliable and accessible after-sales service.
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Help in obtaining grants, like Hydro-Québec’s LogisVert rebates, which we assist with.
For instance, we recently installed a Bosch Climate 5000 wall-mounted air conditioner in a residence in Boisbriand, perfectly sized for a 40 m² living room, with a 25% performance improvement compared to the old system.
Conclusion: your wall-mounted air conditioner’s efficiency depends on your choices
A wall-mounted air conditioner is a long-term investment. Its performance depends on a careful installation, rigorous maintenance, and smart usage. By avoiding the mistakes we’ve outlined here, you ensure your system delivers comfort, energy savings, and durability.
At AirGreen, we bring our hands-on experience, personalized approach, and HVAC service excellence to make your wall-mounted cooling solution a long-term success.
Contact us today for a professional diagnosis or installation.