When a Poor HVAC Installation Turns into a Nightmare in a New Home
In Longueuil, installing a wall-mounted air conditioner in a brand-new family home should have been routine. Unfortunately, when an unprepared contractor attempts to install a system without respecting proper HVAC practices, the consequences can be severe. At AirGreen, we were recently called in to fix a job where a sloppy wall-mounted air conditioner installation not only damaged the walls and floors but also led to destructive water infiltration into the home’s insulation.
This real-life case gives us a concrete lesson: in the world of heating, ventilation, and air conditioning, every detail matters — especially when it involves new construction in Longueuil, on the South Shore, or anywhere in Greater Montréal.
A Real AirGreen Service Call in Longueuil
This past June, our team was contacted by a young family who had just moved into their brand-new bungalow in Longueuil. Less than two weeks after settling in, traces of moisture appeared on the interior wall, just below the unit installed in the living room. The original contractor — now unreachable — had apparently skipped several critical steps in the installation.
Initial Technical Inspection
From the moment we arrived, we identified several glaring errors:
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Improper upward slope on the condensate drain
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No insulation on refrigerant lines, leading to condensation
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Off-centered wall penetration, letting outside humidity in
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Poorly tightened refrigerant fittings, causing a small refrigerant leak
The result: water infiltration into the wall insulation, mold on the drywall, warped flooring, and declining efficiency from the installed Gree Lomo 12,000 BTU wall-mounted unit.
Technical Analysis: What Should Never Be Done
At AirGreen, every HVAC installation follows a precise protocol. Here are the main mistakes made in this case — and what should always be avoided:
Poor Drain Management
Condensation generated by a wall-mounted air conditioner must exit via a slightly downward-sloped hose, leading outside or into a drain. Here, the hose sloped upward slightly, causing hidden water buildup behind the unit.
Missing Pipe Insulation
Without thermal insulation, refrigerant lines cool the surrounding air. In humid conditions, this creates condensation that trickles down inside the walls. A simple insulated sleeve would have prevented the issue.
Botched Wall Penetration
Drilling through an exterior wall requires precision and sealing. In this case, the hole cut through multiple layers without any weatherproof sealant. The result: warm air and moisture continuously entered the wall cavity, weakening the materials.
Improper Refrigerant Connections
Small but constant, a leak of R-410A refrigerant lowered the circuit pressure, reducing compressor output and increasing electricity consumption.
What We Did to Repair and Correct the Installation
Our team tackled the fix in several key steps:
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Complete removal of the wall-mounted unit and partial opening of the inner wall.
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Thorough drying of the insulation using industrial blowers and humidity sensors.
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Replacement of the wall panel and localized antifungal treatment.
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Complete reinstallation of the Gree wall-mounted unit with:
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Proper downward slope on the drain hose
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Reinforced pipe insulation
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Weatherproof caulking around the wall penetration
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Refrigerant pressure test on the entire system
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Final Result
The system now runs flawlessly. Energy consumption is optimized, comfort is consistent, and the family has peace of mind. This project reminds us how important it is to hire certified, experienced installers for any HVAC work in Longueuil, especially in a new home.
Our Recommendations to Avoid This Kind of Disaster
Before Installation
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Check the installer’s credentials and certifications
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Ask for a detailed installation plan
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Make sure the work complies with local building codes
After Installation
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Watch for signs of moisture, strange noises, or inconsistent performance
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Have your unit inspected by an AirGreen technician if you have any doubts
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Schedule an annual HVAC maintenance starting from year one
Why Choose AirGreen for Your Wall-Mounted AC Installation in Longueuil
Our team operates daily in Longueuil, but also throughout Montréal, Laval, the North Shore, and the South Shore, handling everything from wall-mounted AC installations to preventive maintenance and HVAC repairs. Our technicians follow a proven method to guarantee:
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A safe, clean, and long-lasting installation
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Maximum energy efficiency
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Compliance with programs like LogisVert or Rénoclimat
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Reliable and fast after-sales support
In Conclusion: A Poorly Installed Wall-Mounted AC Costs More Than a Skilled Installer
Don’t let a too-good-to-be-true quote put your home’s comfort and structure at risk. A poorly done HVAC installation can lead to repair costs higher than the original system itself. At AirGreen, we do more than install — we protect your investment.