Installing air conditioning in your home or business in Montreal, Laval, Longueuil, the South Shore or the North Shore should never be done on a whim. And yet, at AirGreen, we’ve been called in to deal with catastrophic situations where poorly installed air conditioning systems not only ruined comfort but also damaged buildings or even endangered the safety of the occupants. In this article, our technicians share five real stories, all from our fieldwork, to alert you to mistakes to avoid… and to show you why relying on qualified HVAC installation professionals makes all the difference.
When Amateur Work Gets Expensive: Five Real Cases Seen in and Around Montreal
We’re not trying to scare anyone. But too often, we receive distress calls that could have easily been avoided. Here are five real-life examples where a bad wall-mounted air conditioner installation caused major issues, and where AirGreen technicians stepped in with precision, professionalism, and efficiency to fix the mess.
1. Wall-Mounted AC Half-Hanging in Ville-Marie: A Hazard Over the Sidewalk
In the middle of a heatwave in August, our team responded to an emergency call at a residential building in Ville-Marie, where a Gree wall-mounted air conditioner installed by an uncertified contractor was literally hanging off the second-floor wall and threatening to fall onto the sidewalk.
What we found:
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Wall brackets completely inappropriate, screwed into plaster instead of masonry.
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Drainage routed improperly, causing water infiltration inside the walls.
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No compliant outdoor wall bracket installed.
What we did:
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Full removal of the unit.
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Reinstallation using chemical anchors secured in masonry.
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Installation of anti-vibration wall brackets.
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Drain line redirected to a safe, compliant discharge point.
Thanks to this intervention, the building was made safe and the system was restored to optimal performance, all while complying with the safety standards required in Montreal.
2. Laval Condo: A Compressor Suffocating Inside an Outdoor Closet
In a Chomedey, Laval condo, a Fujitsu KZAH 12,000 BTU wall-mounted heat pump had been installed with its compressor... inside an outdoor closet that had been turned into a hiding spot.
The consequences:
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Constant overheating of the compressor.
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Massive drop in energy efficiency.
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Burnt plastic smell in the living space.
What we did:
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Complete disassembly.
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Relocation of the compressor to a ventilated outdoor concrete base.
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Thorough cleaning of the indoor unit.
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Refrigerant R-32 level checked and corrected.
These kinds of hidden installations are not only ineffective, but outright dangerous. The result: the client now enjoys optimized energy efficiency and a system that’s safe and eligible for the LogisVert grant from Hydro-Québec.
3. Backwards Installation on the South Shore: Indoor Unit in the Basement, Compressor in the Attic
In a home in Brossard, another company had installed a Senville LETO 18,000 BTU wall-mounted heat pump with a totally backward setup: the outdoor unit was placed… in the attic!
The issues:
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Zero accessibility for maintenance.
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High risk of overheating and condensation in the attic.
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Energy efficiency dropped by 40%.
AirGreen's fix:
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Removal and relocation of the outdoor unit to a proper outdoor base.
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Full revision of the refrigerant line installation.
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Addition of certified insulation sleeves suitable for our climate.
Since then, the homeowner has seen a 35% drop in energy bills, and now has peace of mind with a compliant HVAC installation.
4. North Shore: Wall-Mounted AC Installed in a Bathroom With No Ventilation
One particularly tricky case in Terrebonne involved a homeowner who had installed a Tosot 9,000 BTU unit in a small bathroom… without considering the ventilation requirements for the system to function properly.
The result:
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Excessive condensation.
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Mold growing on the walls.
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Constant humidity levels.
What we did:
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Moved the indoor unit to the adjacent bedroom.
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Installed a heat recovery ventilator (HRV) in the bathroom.
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Brought the electrical circuit up to code.
The bathroom’s comfort level was restored, and the moisture issues were permanently resolved.
5. DIY Disaster in Longueuil: No Clearance Around a Bosch BIVA Compressor
We were called out to Longueuil for a Bosch BIVA IDS Premium R-454b compressor that had been installed in a backyard… completely surrounded by a hedge less than 10 cm away.
What happened:
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Poor air circulation.
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Frequent shutdowns.
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Premature wear on the motor.
What we did:
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Trimmed and reshaped the space to meet the minimum clearance requirements (at least 30 cm).
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Cleaned the exterior coil.
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Calibrated the temperature control system.
The unit is now running at full capacity, with an optimized lifespan and energy performance that lives up to Bosch’s standards.
Why Do These Mistakes Keep Happening?
Because too many consumers put their trust in uncertified installers, or they attempt to install complex HVAC systems themselves. The lure of "cheaper" often ends up costing much more just a few months later.
What We Do Differently at AirGreen
At AirGreen, every project is analyzed in detail:
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Personalized thermal load assessment.
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Selection of the right brand and model (Gree, Fujitsu, Bosch, etc.) based on your actual needs.
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Compliance with the Quebec Building Code.
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Guaranteed eligibility for government grants.
Our technicians are certified, continually trained, and fully equipped to work in all types of residential and commercial buildings across Montreal, Laval, Longueuil, the North Shore and the South Shore.
Practical Tips to Avoid a Bad HVAC Installation
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Always ask for a detailed written quote.
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Make sure the installer has a valid RBQ license.
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Ask to see photos of past installations.
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Be wary of prices that seem too good to be true.
Trust the Expertise of AirGreen
Every badly installed air conditioner we repair reminds us why our work matters. It’s not just about cooling or heating — it’s about protecting your investment, your comfort, and your safety.
Don’t take risks with your air conditioning installation. Trust a team that’s known for being thorough, reliable, and passionate: AirGreen.