Accurate diagnosis and efficient repair of a Gree wall system in a Montreal triplex
At AirGreen , we regularly work in typical Montreal residential buildings, where HVAC systems require meticulous attention to maintain both energy efficiency and occupant comfort. In this service call, we were asked to inspect and repair a Gree wall-mounted heat pump installed in a triplex in the Rosemont–La Petite-Patrie neighborhood , a dense residential area with narrow buildings often exposed to extreme temperature variations.
📍 Context of the intervention
The customer contacted us after noticing a significant drop in the efficiency of their heat pump. Despite the apparent good condition of the outdoor condenser (visible in the photo above, installed under a ground-floor window), the indoor unit was no longer able to maintain a stable temperature in the home.
The Gree model, typically known for its reliability and high seasonal efficiency , was exhibiting symptoms suggesting a refrigerant pressure problem or a fault in the indoor temperature sensor . The system, powered by an independent power line and installed near a wooden balcony, had been exposed to a buildup of dust and seasonal moisture.
🧰 Steps of diagnosis and repair
1. Initial inspection and pressure check
Upon our arrival, our certified technician performed a complete check of the refrigeration circuit . The pressures measured were lower than Gree's recommended nominal values, indicating a minor leak in the copper line connecting the wall unit to the outdoor compressor.
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Low pressure measured : 65 psi instead of the expected 110 psi.
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Abnormal evaporation temperature : 4°C instead of 8–10°C.
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Observation : Oil accumulation on a slightly corroded flare fitting.
2. Leak detection and correction
We isolated the faulty line and performed a nitrogen gas test to confirm the leak. Once located, the damaged area was silver-soldered after cleaning and sanding the copper. We then pulled a complete vacuum from the system for 45 minutes to remove any moisture.
3. Recharging R410A refrigerant
The system was recharged with R410A according to the exact specifications of the manufacturer Gree, at a rate of 1.2 kg , following the subcooling method. This step allowed the nominal pressures to be restored and ensured stable operation of the compressor.
4. Indoor sensor calibration and performance test
A recalibration of the interior temperature sensor was performed via the electronic control board. Final tests demonstrated optimal performance:
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Blowing temperature : 9°C lower than ambient air.
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Stable compression cycle .
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No vibration or abnormal noise .
🧩 Technical challenges encountered
Access to the outdoor unit proved challenging due to the narrow yard and overhanging balcony . Additionally, the electrical wiring and refrigerant line configuration along the facade required careful handling to avoid damage to the vinyl siding.
Our technicians used suitable handling supports and an anti-vibration insulating mat to stabilize the condenser during restart.
🌡️ Final result: comfort restored and performance optimized
After the repair, the Gree heat pump returned to its original performance , providing stable heating and cooling for the ground floor apartment. The client noted a reduction in operating noise and improved temperature distribution in the main rooms.
We also carried out a preventive check of the electrical connections and advised the customer to clean the filters every three months to extend the life of the device.
💡 AirGreen Recommendations
To prevent this type of breakdown from recurring, we recommend:
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Regularly check refrigerant connections after seasonal changes.
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Install a condenser guard to limit dust and moisture deposits.
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Subscribe to an annual AirGreen maintenance plan , which includes complete cleaning of the coils, pressure checks and electronic card inspection.
In summary
This intervention perfectly illustrates the rigor of our team in the diagnosis and repair of Gree wall-mounted heat pumps in Montreal. Thanks to our methodical approach and the expertise of our certified technicians, the system has regained optimal performance, guaranteeing lasting comfort and maximum energy efficiency .
AirGreen Air Conditioning & Heating — Your trusted HVAC partner in Montreal, Laval and on the North and South Shores.
Contact us for any repair, installation or maintenance of your Gree, Fujitsu, Midea, Sharp or other recognized brand system.