A high-rise intervention to restore the comfort of a commercial building
When a Fujitsu wall-mounted heat pump breaks down on a flat roof, repairs require not only expertise but also careful planning. This is precisely the challenge we recently addressed in Côte-des-Neiges–Notre-Dame-de-Grâce , a Montreal area where several mixed-use buildings (retail and office) rely on rooftop HVAC systems.
The call came from the manager of a small office building, concerned that the Fujitsu system had been without heating or cooling for several days. On site, our AirGreen team quickly realized that it was a critical failure of the outdoor module .
Diagnosis: Compressor inactive and control board defective
The outdoor unit, installed on an elevated structure, was exposed to harsh weather conditions—humidity, frost, and frequent rain. Our visual inspection revealed several signs of deterioration:
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Moisture buildup and corrosion on electrical terminals.
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Traces of oxidation on the compressor connectors.
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A functional fan , but a completely silent compressor.
After testing with a multimeter and checking circuit continuity, we isolated the cause: an electronic control board had stopped sending the start signal to the compressor.
This problem is common on units installed on roofs exposed to extreme temperature fluctuations. Without prompt intervention, it can cause an electrical overload and damage the main motor.
Intervention: replacement of the card and resealing of the connections
Our team carried out a complete repair following the safety protocols specific to working at height:
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Power cut and safe disconnection of the system.
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Disassembly of the control panel to access the electronic card.
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Installation of a new original Fujitsu card , compatible with the AOU12RLFW range module.
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Checking the supply voltage (240 V stable).
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Sealing and protecting electrical connections using heat shrink tubing and dielectric sealant.
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Clean the compressor compartment with compressed air and mild degreaser.
Once the board was replaced, powering up confirmed the compressor was working properly: the inrush current was stable, the discharge pressure was correct and the blowing temperature was within Fujitsu specifications.
Result: restored performance and increased reliability
After rebooting, we performed several performance tests:
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Blown air temperature in air conditioning mode: 9°C.
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Recovery temperature : 22°C.
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Differential of 13°C , proof of excellent heat transfer.
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Nominal power consumption and absence of abnormal vibrations.
We also checked the condensate drainage , the tightness of the refrigerant connections and the proper balance of the fan. The unit was now operating quietly and efficiently .
To ensure the durability of the system, we have installed additional protection against water infiltration on the electrical connections and recommended biannual preventive maintenance (spring and fall).
The Importance of Maintenance for Rooftop Systems
Outdoor units installed on roofs are more exposed to climatic hazards:
wind, rain, snow, UV, extreme temperature variations. These conditions accelerate the wear of electronic components and can compromise the overall performance of the HVAC system.
At AirGreen, we emphasize a few best practices :
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Check the condition of the electrical connections at each maintenance.
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Inspect the anti-vibration mounts and the mounting structure.
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Clean the condenser fins regularly to prevent overheating.
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Use corrosion protection in wet areas.
Regular maintenance can extend the life of a Fujitsu heat pump by more than 30% , while maintaining optimal energy consumption.
AirGreen: HVAC expertise in Montreal and on the North and South Shores
Whether on a building roof in Montreal , in a house in Laval or a business in Brossard , our certified technicians intervene quickly to repair, maintain and optimize Fujitsu, Gree, Midea, Sharp, Lennox HVAC systems and more .
We master all technologies:
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Wall-mounted and central heat pumps
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MultiZone and VRF Systems
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Wall-mounted and ducted air conditioners
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Air exchangers and HVAC accessories
Our goal: to offer a fast, sustainable and transparent service, adapted to both residential and commercial needs.
Conclusion: a preventive and lasting repair
This Fujitsu heat pump repair in Côte-des-Neiges–Notre-Dame-de-Grâce demonstrates the importance of rigorous maintenance of rooftop HVAC systems. By replacing the circuit board and securing the connections, AirGreen not only restored the unit's performance but also prevented costly future breakdowns .
At AirGreen, every service call is handled with the same level of precision and professionalism—because your comfort deserves trusted expertise.