Diagnosis on a flat roof in Laval: an outdoor unit in difficulty
At AirGreen , our technicians were recently called to Sainte-Dorothée , a residential area of Laval , for a service call on a Gree wall-mounted heat pump installed on the flat roof of a multi-family building. The customer contacted us after noticing that the system was no longer providing adequate heating and that the outdoor unit seemed to be producing an abnormal noise accompanied by excessive vibrations .
Our team dispatched a certified technician to perform a complete system diagnosis . Upon arrival on the roof, he noticed that the heat pump—a Gree Multi-Zone model powering multiple indoor units—was resting on concrete supports and galvanized bars , a typical configuration to ensure stability on a bituminous membrane.
Step 1 – Visual inspection and initial findings
The first check focused on the refrigeration and electrical connections. Several clues suggested a mechanical vibration problem :
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The refrigerant pipes were lightly touching the masonry of the adjacent chimney,
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The silent blocks under the support rails were worn,
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A slight oil leak was visible near a flare fitting.
These symptoms already pointed the diagnosis towards a partial loss of refrigerant charge , causing a drop in pressure and mechanical imbalances in the compressor.
Step 2 – Electrical and refrigeration checks
After turning off the main power, the technician performed a continuity test on the external circuit board and took a static pressure reading using R-32 gauges. Result:
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Abnormally low pressure in heating mode,
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Difficult compressor start,
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Higher than normal power consumption.
These values confirmed the diagnosis: minor leak on the liquid line .
Step 3 – Repair and recharge the refrigeration circuit
To correct the problem, our technician:
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Tightened and remade the flare joint using a calibrated torque meter,
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Replaced the damaged silentblock to reduce vibrations,
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Performed a complete vacuum draw of the circuit,
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Recharged the system with R-32 according to Gree specifications, respecting the exact weight indicated on the nameplate,
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Checked for leaks with nitrogen and electronic detector.
Once the system was back in operation, the pressures and blowing temperatures returned to optimal values. Compressor noise faded, and the indoor units returned to uniform heat distribution throughout the homes.
Step 4 – Final verification and recommendations to the client
Before leaving the premises, our team carried out a complete analysis of the support points and recommended to the client:
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To clean the condenser fins twice a year,
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To maintain a clearance of at least 30 cm around the unit ,
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And have the system inspected annually , especially before the cold season.
We also added anti-vibration mats under the metal supports to reduce sound transmission to the roof structure—a particularly effective improvement for multi-unit buildings.
AirGreen expertise: reliability and performance guaranteed
This intervention demonstrates our expertise in repairing residential and multi-zone HVAC systems , even in demanding technical contexts such as flat roof installations. At AirGreen, we know that every uncomfortable minute counts—that's why our technicians are trained to diagnose quickly, repair efficiently, and extend the life of equipment.
Whether it's a Gree, Fujitsu, Sharp or Midea heat pump , our team operates in Montreal, Laval, Longueuil, on the North Shore and the South Shore to ensure fast, professional and long-lasting service.
Thanks to this repair, the Sainte-Dorothée customer has regained optimal comfort , stable energy consumption , and the peace of mind of a well-maintained system.