When the performance of a rooftop HVAC system requires expert attention
At AirGreen , we are regularly called upon to work on complex HVAC installations located on the flat roofs typical of Montreal apartment buildings. Recently, our team was called upon for a service call in Outremont , where several Fujitsu wall-mounted heat pumps were installed on a gravel roof, exposed to the elements.
Context of the intervention
The client, the owner of an apartment building, contacted us after noticing a significant drop in the performance of several Fujitsu units. Tenants were complaining of a lack of heating in the mid-season, despite the indoor units apparently functioning properly.
Upon arrival, our certified technicians observed four Fujitsu HFI outdoor units lined up on the roof. These units, while robust, were clogged with dust, pollen, and debris that had accumulated over time —a common occurrence on flat roofs in urban areas.
Detailed diagnosis
After a complete inspection:
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The air filters in the indoor units were clean, eliminating an internal cause.
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A refrigerant pressure reading revealed an imbalance between two circuits , indicating a minor leak on a refrigeration line .
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One of the outdoor fans was also showing signs of wear on the bearing , causing intermittent noise.
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Finally, the presence of gravel blown by the wind had partially obstructed the condenser fins.
This type of multiple failure is common when multiple heat pumps operate side by side in an open environment such as a building rooftop. The proximity of the units can reduce airflow, causing the compressor to overheat and reducing energy efficiency .
Steps of repair
Our technicians undertook a complete maintenance and targeted repair :
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Deep cleaning of condensers with a soft jet and a biodegradable product suitable for aluminum surfaces.
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Leak detection carried out using an electronic detector, locating the micro-leak on a flare fitting.
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Tightening and replacing the gasket of the affected fitting.
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Refrigerant gas upgrade R-410A according to Fujitsu manufacturer specifications.
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Lubrication and testing of fan motor with excessive play.
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Final check of pressures, air flow and discharge temperature.
Results and performance optimization
After these interventions, the four Fujitsu units returned to their optimal performance. During the load test:
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The indoor blowing temperature reached 28°C in heating mode, confirming restored efficiency.
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The outside noise level has decreased by almost 40%, a sign that the repaired fan is properly balanced.
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Tenants quickly reported improved comfort in the accommodations.
We also advised the owner to perform semi-annual preventive maintenance , which is particularly important for flat roof installations exposed to dust and Montreal's climatic variations.
Maintenance Tips for Apartment Building Owners
To extend the life and maintain the efficiency of wall-mounted heat pumps:
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Clean the fins regularly and remove debris around the outdoor units.
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Avoid placing multiple units too close to each other to maintain good air circulation.
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Schedule professional maintenance in the spring and fall , before peak heating or cooling times.
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Watch for unusual noises : these are often the first signs of worn bearings or unbalanced blades.
At AirGreen , we offer our expertise to building owners and managers throughout Greater Montreal , including Laval, Longueuil, the North Shore and the South Shore . Our services are always carried out according to the strictest HVAC industry standards, using modern diagnostic tools and original parts.
A trusted team, high-performance systems all year round
With our field experience and in-depth knowledge of Fujitsu HFI systems , we offer long-lasting repairs and preventative maintenance tailored to each configuration. Whether your system is installed on a roof, in a technical room, or on a facade, our goal remains the same: to restore your comfort and optimize the energy efficiency of your equipment.