Water infiltration indicating an internal drainage problem
During a service call in Rosemont–La Petite-Patrie , Montreal, our AirGreen team was contacted about a Gree wall-mounted air conditioner with water marks on the wall below the indoor unit. The customer had noticed water droplets dripping directly from the bottom panel for a few days, accompanied by a gurgling noise every time the compressor started.
This type of problem, although common, can have several possible origins: a blocked condensate drain , an incorrect slope of the drain pipe , or even partial ice formation on the evaporator coil.
Diagnosis: between excessive humidity and internal accumulation
Upon arrival, we undertook a visual and thermal inspection of the unit. Several clues quickly confirmed the cause of the problem:
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Vertical drain marks on the wall, clearly visible under the unit housing.
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An open service hatch below, indicating that a previous maintenance attempt may have been interrupted.
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An uninsulated drain pipe that was slightly bent into the wall, which encouraged water to stagnate.
Using a low-pressure blow-out test, we confirmed that the drain was partially blocked by a buildup of dust and algae—a common occurrence when seasonal cleaning is neglected.
Complete intervention: restoration of the drainage system
To ensure a lasting repair, our technicians carried out several precise technical steps:
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Disassembly of the lower panel and inspection of the condensate chute.
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Complete drain cleaning with a vacuum pump and dry air jet to remove any organic blockages.
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Disinfection of the evaporation tank using an antibacterial solution specially designed for Gree systems.
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Flushing the outlet pipe and checking the slope to the outside of the building.
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Hot flow test : the system was returned to air conditioning mode to observe the formation and natural drainage of condensate.
The water flow has been restored normally, without leaks or stagnation.
Additional analysis: importance of good wall positioning
Looking at the wall configuration, we also noticed that the unit was installed above a staircase , in a recess. This type of location—often chosen for its aesthetic discretion—can sometimes limit airflow around the unit and increase localized humidity , especially when the adjacent room is poorly ventilated.
We therefore recommended to the client:
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Add a supplemental dehumidifier during periods of high heat.
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Schedule annual AirGreen maintenance , including complete cleaning of the condensate tray and evaporator.
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Check that the drain pipe is properly insulated in the partition to avoid internal condensation.
Result: a dry wall and a high-performance system
After the repair, the Gree unit returned to quiet and efficient operation. After several test cycles , no moisture was visible on the wall. The customer was able to put their air conditioning back into operation with confidence, reassured by our repair guarantee.
This intervention perfectly illustrates how a simple drain clog can cause visible damage , but easily avoidable thanks to regular maintenance by a certified HVAC professional .
AirGreen: Reliable HVAC Repairs in Montreal and Throughout Greater Montreal
At AirGreen , we operate daily in Montreal, Laval, Longueuil, on the North Shore and the South Shore for repairs to wall-mounted air conditioners, wall-mounted heat pumps and MultiZone systems .
Our priorities:
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Accurate and transparent diagnostics .
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Durable repairs , with original parts.
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Personalized maintenance tips to extend the life of your system.
Even slight water leakage can be a sign of a more serious problem. Don't wait for paint to deteriorate or mold to set in —contact AirGreen at the first sign of moisture.