An extreme case that highlights the vital importance of regular maintenance for wall-mounted air conditioners
In the field of residential HVAC in Montreal, few situations are as surprising and concerning as the discoveries made during the late servicing of a wall-mounted air conditioner. At AirGreen, we recently encountered a unique case in a residential building in Longueuil, on the South Shore of Montreal, which perfectly illustrates how neglecting maintenance can impact performance, air quality, and the overall lifespan of an HVAC system.
An urgent call in Longueuil: a wall-mounted air conditioner neglected for 5 years
Our team was contacted by a homeowner complaining of a drastic drop in the performance of his Gree Lomo 12,000 BTU wall-mounted air conditioner, installed in 2019. This client had never performed any HVAC maintenance since the unit was installed, mistakenly believing that a quiet system automatically meant it was working well. Unfortunately, this belief is still common, especially among first-time homeowners.
Upon our arrival, a strong musty odor was coming from the indoor unit. Visually, the grille was clogged—but that was just the beginning of what we were about to discover…
Extreme buildup of dirt, mold, and debris
As soon as the front panel was opened, our technicians were met with a shocking sight:
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The filters were completely clogged, coated with a thick mix of dust, pet hair, and greasy particles.
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The evaporator coil was covered in black mold, severely reducing heat exchange.
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The drainage tray was blocked, causing water to back up into the adjacent wall, encouraging hidden fungal growth.
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The blower fan was unbalanced due to massive buildup, causing vibration and noise each time it turned on.
This extreme situation posed not only a risk to the health of the occupants — particularly respiratory health — but also jeopardized the structural integrity of the unit itself.
A full restoration: cleaning, disinfecting, and recalibrating
Our intervention involved several critical steps to restore performance and ensure a healthy HVAC system:
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Complete disassembly of the wall-mounted unit, allowing full access to the coil, drain tray, and fan.
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High-pressure cleaning with biodegradable, HVAC-safe products.
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Antifungal and antibacterial treatment applied to all internal surfaces.
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Clearing the condensate drain using a professional HVAC plumbing vacuum.
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Reassembly and recalibration of the unit, followed by a test run to confirm everything was functioning correctly.
After this thorough restoration, the unit returned to peak operation. The air was not only cooler, but noticeably fresher. The client immediately noticed a reduction in odors, better airflow, and lower electricity consumption.
Why annual maintenance is essential in Montreal, Laval, and on the South Shore
Quebec’s climate—with its harsh winters and increasingly hot summers—puts wall-mounted air conditioners under significant stress. Humidity, dust, pollen, and even pet hair accumulate inside the units, especially in residential areas with dense greenery like Laval and Brossard.
At AirGreen, we strongly recommend annual preventative maintenance that includes:
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Cleaning of filters and coils
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Inspection of refrigerant levels
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Electrical connection checks
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Full antibacterial disinfection
This not only extends the lifespan of the equipment, but also significantly reduces costly breakdowns and improves indoor air quality — a crucial benefit, especially in homes with young children or elderly residents.
Common mistakes to avoid with a wall-mounted air conditioner
This case in Longueuil perfectly illustrates the most common mistakes we see:
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Ignoring early warning signs like reduced power or unusual smells.
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Delaying annual servicing, especially after two years of use.
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Relying on the unit as an air purifier without any cleaning.
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Leaving the unit unused all winter without proper protection.
These mistakes, while common, are easily avoidable when following the guidance of a certified HVAC contractor like AirGreen.
What this service call says about our approach
At AirGreen, every job is an opportunity to demonstrate our technical expertise, our educational approach with clients, and our commitment to long-lasting service. We don’t just clean—we educate our clients, visually show them the damage caused by neglect, and provide a detailed service report with personalized recommendations.
Our technicians, trained to the highest standards in the industry, respond quickly across Montreal, Laval, Longueuil, and throughout the North Shore and South Shore.
Practical tips: how to maintain your wall-mounted air conditioner
Here are some easy steps to take between professional service visits:
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Clean the filters monthly during heavy use.
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Keep the area around the wall unit clear.
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Stay alert to unusual noises or smells.
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Contact a specialist at the first sign of trouble.
AirGreen: your trusted partner for HVAC installations and maintenance
In addition to maintenance, we offer professional installation of wall-mounted air conditioners from top brands like Gree, Fujitsu, Daikin, Sharp, and Tosot, throughout the Greater Montreal Area. Many of our services are eligible for government grants such as Hydro-Québec’s LogisVert program.
Conclusion: A situation that could have been avoided—but full of important lessons
The servicing of this Gree 12,000 BTU wall-mounted air conditioner in Longueuil shows the real impact that poor maintenance can have on performance, health, and your wallet. Thanks to our expertise, the unit was saved, but this experience remains a powerful reminder: just because a wall-mounted air conditioner is quiet doesn’t mean it’s healthy or functioning properly.
Trust your comfort to a professional team. Contact AirGreen today for a complete HVAC maintenance, an evaluation of your current setup, or to discuss your energy retrofit projects in Montreal, Laval, Longueuil, on the North Shore or South Shore.