A roof intervention typical of the Montreal residential sector
At AirGreen , we frequently carry out work on the roofs of residential buildings in the Rosemont–La Petite-Patrie area, where several condominiums have chosen Gree MultiZone heat pumps to ensure four-season comfort. This type of system, particularly effective in urban areas, can serve several interior zones from a single outdoor compressor.
Our client, the owner of a duplex converted into a condominium, called us after noticing a simultaneous loss of performance on two indoor units connected to his MultiZone system. The air supply was lukewarm, even in cooling mode, and the outdoor unit on the roof produced an intermittent whistling noise , indicating a refrigeration problem.
Inspection and diagnosis: understanding the origin of the breakdown
Upon our arrival on the roof, our technician performed a complete diagnostic of the two outdoor condensers. The installation rested on a treated wood support, typical of flat roof installations in Montreal. After a visual inspection and pressure check, the following observations were made:
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Minor leak of R-410A refrigerant on one of the lines connecting the main compressor to the living room evaporator.
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Deteriorated thermal insulation , exposing the line to strong temperature variations.
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Accumulation of debris and dust around the exchangers, reducing heat exchange.
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Crankcase heater disconnected , which explains the starting difficulties in cool weather.
Using our electronic diagnostic tools, we confirmed that the low pressure was below the nominal value , causing overall system underperformance.
Repair steps: precision and rigor on the roof
The repair work was carried out in several stages, in accordance with safety protocols for roofing work:
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Safe recovery of existing refrigerant using a certified reclaimer, in accordance with environmental standards.
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Repair of the leak by silver soldering and replacement of the damaged copper sections.
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Complete replacement of thermal insulation with insulation resistant to UV and extreme temperature conditions.
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Nitrogen leak test for 45 minutes to validate the perfect hermeticity of the circuit.
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Recharge the system with R-410A refrigerant according to the exact charge from the Gree manufacturer.
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Checking the crankcase resistance and reconnecting to the electrical circuit.
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Complete cleaning of the condenser with gentle steam and checking of the air flow.
After being put back into service, the heat pump returned to optimal performance , with blowing temperatures measured at 8°C in air conditioning mode and 41°C in heating mode .
A technical repair, but also a preventive one
This intervention made it possible to resolve the immediate breakdown, but also to prevent several future risks . On MultiZone systems, a small leak or pressure imbalance can quickly affect all connected zones . By restoring the watertightness and insulation of the circuit, we ensured:
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Balanced performance on every indoor unit.
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A reduction in energy consumption .
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A reduction in operating noise .
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Extended compressor life .
The customer immediately noticed the difference: fresh air was circulating in all rooms again, and the compressor was running smoothly and quietly.
The Importance of MultiZone Heat Pump Maintenance
Gree MultiZone systems , highly prized in Montreal for their efficiency and flexibility, require regular maintenance to maintain their performance. We recommend in particular:
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Cleaning the condenser and filters twice a year.
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A refrigerant level inspection every 24 months.
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Checking the insulation of ducts exposed to the weather.
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Monitoring of vibrations and roof mounting brackets .
Proper maintenance helps prevent costly breakdowns, especially in buildings where multiple zones rely on the same compressor.
AirGreen: recognized expertise in HVAC repair in Montreal
At AirGreen , we combine technical expertise with environmental compliance to deliver safe, sustainable repairs . Our team is trained to work on all brands of heat pumps, including Gree, Mitsubishi, Midea, Sharp, Lennox, Goodman, and Bosch .
Our interventions in Rosemont–La Petite-Patrie , but also in Laval, Longueuil, and on the North Shore and the South Shore , are always carried out with the same attention to detail:
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Accurate diagnosis using state-of-the-art equipment.
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Repairs guaranteed to comply with manufacturer recommendations.
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Courteous and transparent service , with no hidden costs.
End result: restored performance and satisfied customer
Following our intervention, the client regained a high-performance system capable of heating and cooling the entire duplex efficiently. Temperatures are now stable, and energy consumption has returned to normal.
This repair perfectly illustrates AirGreen's expertise in complex diagnostics and preventive maintenance on multi-zone HVAC systems installed on Montreal roofs.
Areas served : Montreal, Laval, Longueuil, North Shore, South Shore
Service offered : Repair, maintenance, installation and inspection of residential and commercial HVAC systems