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Réparation d’une thermopompe murale Gree à Rosemont–La Petite-Patrie
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Repair of a Gree wall-mounted heat pump in Rosemont–La Petite-Patrie

An intervention on a Montreal roof for a stopped heat pump

At AirGreen , we are regularly called upon to work on residential and multi-unit HVAC systems located on the roofs of buildings in Montreal. In this service call, our team was dispatched to Rosemont–La Petite-Patrie to diagnose and repair a Gree wall-mounted heat pump that refused to start at the beginning of the warm season.

The context of the intervention

The manager of a recent building contacted us after noticing that several Gree wall-mounted units on the roof were no longer responding to the indoor control. One of the outdoor units—the one pictured—was showing signs of premature wear:

  • Fan blocked ,

  • Accumulation of dust and gravel ,

  • And a metallic noise at startup, followed by a complete shutdown of the compressor.

The goal was clear: restore air conditioning before the heat peak, while ensuring the safety and durability of components exposed to the elements.

Diagnosis: A capacitor and exposure problem

Our technicians began with a complete roof diagnostic, checking the condition of the electrical supplies and refrigeration connections . Key observations:

  • Stable 240V power supply , but no compressor start.

  • Swollen starting capacitor : a clear sign of failure.

  • Exterior fan blocked by debris and gravel from flat roof.

  • Main electronic board (PCB) intact, but slightly oxidized by humidity.

After these checks, the fault was attributed to a faulty capacitor , aggravated by direct exposure of the unit to external conditions (sun, rain, fine dust).

Repair: replacement and reconditioning of the unit

  1. Safely disconnect the power supply before intervention.

  2. Disassembly of the side panel to access the electrical compartment.

  3. Replaced the starting capacitor with an original Gree model, rated for the 12,000 BTU series.

  4. Complete cleaning of the fan and condenser with compressed air and a gentle jet, to remove dust and gravel.

  5. Application of a dielectric protector to the connectors to limit future oxidation.

  6. Restart and load test: after a few seconds, the fan and compressor started without any anomalies.

Result: a return to full performance

After 20 minutes of operation, the Gree heat pump reached optimal thermal efficiency , producing air at 7°C at the indoor outlet .
The building manager was able to observe an immediate return of comfort in the connected units.
Additionally, a leak test on the Schrader valves confirmed that no refrigerant leaks were present.

Prevention: Protect flat roof units

This type of roof installation is common in Montreal, but exposes the systems to several risks:

  • Accumulation of gravel and debris , blocking the fan.

  • Solar overheating in summer if units are not protected.

  • Excessive condensation in winter can corrode connections.

💡 AirGreen Tip : Adding a galvanized protective cover or UV shield can extend the life of compressors and condensers on flat roofs.
Annual maintenance performed by our certified technicians is strongly recommended before each cooling season.

AirGreen expertise on Gree systems

As recognized HVAC specialists in Montreal, Laval, Longueuil, the North Shore and the South Shore , we regularly work on Gree heat pumps . These systems offer reliable performance, but require rigorous maintenance to ensure their longevity.
Our interventions include:

  • Complete electronic diagnostics (PCB board, sensors, probes).

  • Replacement of original Gree components .

  • Recharge with R-410A or R-32 refrigerant depending on the model generation.

  • Optimization of SEER efficiency and defrost cycles.

A repair that extends the life of the system

Thanks to this quick repair, the Rosemont building was able to avoid a complete unit replacement, while ensuring reliable operation for the summer season.
A simple capacitor failure could have ultimately caused the compressor to overheat — a much more expensive repair.
Our preventive and methodical approach has made it possible to protect the client's investment while guaranteeing immediate comfort for the occupants .

AirGreen Air Conditioning & Heating
Your trusted partner for the repair, maintenance and installation of Gree HVAC systems and other major brands, throughout Montreal, Laval, Longueuil, North Shore and South Shore .