An intervention on a flat roof in the middle of summer
In the middle of June, our AirGreen team was dispatched to Rosemère , on Montreal's North Shore , for an unusual service call: a Comfortmaker wall-mounted heat pump installed directly on the flat roof of a residential building. The customer had reported that their system had not been producing any cooling for several days, despite the fan apparently operating normally.
Diagnosis: A communication and power problem
Upon our arrival, a quick visual inspection revealed exposed and oxidized wiring at the electrical connection box. The unit, mounted on treated wood supports to isolate vibration, showed signs of prolonged exposure to sunlight and humidity—conditions typical of flat roofs in the Rosemère residential sector.
After measuring the supply voltage and checking the continuity of the cables, our technician identified the cause:
A corroded main connector prevented proper communication between the indoor unit and the outdoor compressor. This defect, often subtle, causes the electronic board to jam and prevents the refrigeration cycle from starting.
Specific steps of repair
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Securing the station and cutting off the power supply : As a safety measure, we disconnected the unit at the circuit breaker before any handling.
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Complete cleaning of the electrical compartment : The terminals were dismantled and cleaned using an antioxidant product and a soft wire brush .
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Replaced the corroded connector with a new part insulated with dielectric silicone.
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Check low voltage wiring (communication signal) and tighten phase terminals.
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Restarted the system and read the refrigeration pressures : the observed values were in accordance with the Comfortmaker standards for R-410A.
After restarting, the heat pump resumed stable operation, displaying a blowing temperature 12°C lower than the ambient temperature — proof of optimal performance.
Prevention and best practices for rooftop installations
Flat roof installations , common in Rosemère, Lorraine and Boisbriand, expose devices to extreme weather conditions : solar radiation, stagnant humidity, snow in winter. These factors accelerate corrosion, especially on unprotected connectors and housings.
At AirGreen , we insist on the following measures to extend the life of Comfortmaker and other brand systems:
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Use waterproof electrical boxes with silicone gaskets.
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Protect connections with dielectric components .
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Raise the unit on galvanized anti-vibration mounts rather than raw wood.
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Perform a semi-annual visual inspection (spring and fall).
These simple precautions prevent many electrical breakdowns and guarantee quiet and stable operation all year round.
AirGreen expertise: speed, rigor and security
This type of failure requires not only in-depth knowledge of Comfortmaker control circuits , but also great vigilance in matters of electrical safety on the roof .
Our technicians are trained and certified RBQ and CCQ , and always work in pairs for installations at height.
Each repair is followed by a technical report detailing the actions carried out, operating values and maintenance recommendations.
Final result: restored comfort and a more reliable installation
At the end of the intervention, the customer found a stable interior temperature and a completely silent device.
Replacing the connector eliminated the communication errors and restored refrigerant flow throughout the system.
We also have:
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Cleaned the condenser fins.
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Checked the insulation of the refrigeration lines.
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Adjusted the slope of the condensate drainage pipes.
These adjustments, although minor, optimize energy performance and reduce the risk of ice in winter .
Conclusion
This repair of a Comfortmaker wall-mounted heat pump in Rosemère demonstrates the importance of accurate diagnosis and rigorous maintenance, especially for rooftop installations.
At AirGreen , we make every effort to ensure the reliability and durability of HVAC systems, whether installed in condos, houses or on flat roofs.
Every intervention is an opportunity to restore comfort—effectively, sustainably, and safely.
Warning:
This article illustrates a typical real-life repair case performed by AirGreen. Situations may vary depending on the model, age, and installation conditions of your HVAC system. For any abnormalities, contact a certified technician.