Optimizing an old wall-mounted air conditioner: balancing energy savings and comfort
At AirGreen, our expertise in HVAC systems in Montréal, Laval, Longueuil, North Shore and South Shore has brought us into many homes and businesses dealing with aging wall-mounted air conditioners. These units, sometimes 10 to 15 years old, can become major energy drains without their owners even realizing it. Yet, a poorly maintained or outdated HVAC installation can cost hundreds of extra dollars every summer, while significantly reducing indoor comfort.
This article walks you through five actionable tips to improve the efficiency of an older wall-mounted air conditioner, while showcasing real-life service calls we’ve handled at AirGreen to fix this exact issue.
Telltale signs that your air conditioner is wasting energy
Before jumping into solutions, it’s important to recognize the signs of an inefficient unit:
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Takes longer to cool than it used to
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Unusual noises or vibrations
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Noticeable spike in your electricity bill during summer
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Air isn’t as cool, or the room feels humid
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Outdoor unit gets hot or the fan is stuck
We were recently called to Longueuil by a customer whose 18,000 BTU wall-mounted AC unit from an unknown brand was struggling to maintain temperature despite regular cleanings. The diagnosis: a clogged evaporator coil, low refrigerant level, and an indoor fan clogged with dust.
1. Clean the filters and coils regularly
Clogged air filters are responsible for nearly 30% of energy loss in wall-mounted air conditioners. They restrict airflow, forcing the unit to work harder and consume more electricity.
AirGreen Tip: Clean the filters once a month during the cooling season. If you have pets or heavy usage, do it more often. Don’t forget to have the evaporator and condenser coils cleaned by a certified technician every year.
Real example: In Boisbriand (North Shore), a rental property owner contacted us about a Toshiba 24,000 BTU wall-mounted unit that was heating instead of cooling. After a deep cleaning of the coils and filters, performance increased by 42%, confirmed by a static pressure test.
2. Check the refrigerant level
Low refrigerant levels often signal a leak and make the unit run longer to reach the desired temperature. Over time, this can damage the compressor.
Typical AirGreen call: In Laval, we were asked to inspect a 12,000 BTU Senville Leto wall-mounted unit that kept shutting off. A pressure test revealed a microscopic leak at the Schrader valve. After repairing it and recharging with R-410A, the system was back to full performance.
3. Optimize the unit’s location and airflow direction
A poorly positioned wall-mounted air conditioner may get direct sun exposure or be blocked by furniture, limiting airflow.
Best practices include:
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Avoid installing on south-facing walls without sun protection.
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Leave at least 15 cm of clearance around the wall unit.
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Face the unit toward the main living area for even cooling.
Optimized installation example: In Boucherville (South Shore), we moved a Panasonic 18,000 BTU unit 30 cm away from a hanging light fixture that was blocking airflow. The result: a 1.8°C reduction in cooling time to reach the set temperature.
4. Install a smart thermostat or timer
Older wall-mounted units often lack timers or precise temperature control. Adding a smart thermostat or timer can dramatically reduce unnecessary run times.
AirGreen solution: We recently equipped a 15,000 BTU Haier unit in Saint-Bruno with a WiFi smart control module. The client can now schedule cycles based on occupancy and humidity levels, saving 20% in energy consumption in the first month alone.
5. Have your HVAC system inspected by a professional
Even if you maintain the basics, only a certified technician can accurately assess the overall condition of your HVAC installation. At AirGreen, our maintenance service includes:
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Refrigerant circuit inspection
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Airflow and output temperature measurements
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Electrical connection checks
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Energy efficiency evaluation (SEER/EER)
Real testimonial: In Montréal, a customer in Rosemont thought his 10-year-old Daikin wall-mounted AC needed replacing. After a full inspection and capacitor replacement, the unit was back to nearly original efficiency for a fraction of the cost of a new system.
When is it time to replace your wall-mounted air conditioner?
Despite best efforts, sometimes the unit has simply reached the end of its useful life. Here’s when to consider replacing it:
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Over 12 years old
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Frequent breakdowns or hard-to-find parts
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Maintenance costs exceed 30% of a new unit’s price
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Noisy operation despite cleanings
In that case, we recommend high-efficiency models, such as:
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Gree Lomo and Sapphire (R-32)
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Sharp ZU1 (high-performance inverter)
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Fujitsu KZAH (ENERGY STAR® certified)
These models are often eligible for Hydro-Québec’s LogisVert grants, which can go up to $2,172, depending on BTU and energy efficiency levels.
Conclusion: Trust AirGreen’s expertise
An aging wall-mounted air conditioner isn’t the end of the world. With a few easy steps, professional checkups, and sometimes a well-timed upgrade, you can regain comfort, cut energy costs, and enjoy peace of mind.
At AirGreen, we support you every step of the way: maintenance, diagnosis, repair, or full replacement. Our deep understanding of HVAC needs in Montréal, Laval, Longueuil, North Shore, and South Shore truly makes a difference.
Need a checkup or maintenance for your old air conditioner? Contact us today for a no-obligation evaluation.