A service call on a flat roof in Montreal
At AirGreen , we regularly work on systems installed in residential buildings in the Rosemont–La Petite-Patrie neighborhood of Montreal, where outdoor units are often installed on flat roofs. It was in this context that we were called to diagnose a Gree wall-mounted heat pump whose compressor refused to start despite the heating demand.
The building owner, concerned about the decline in performance, noticed that the indoor unit was blowing lukewarm air and that the power consumption seemed abnormally high. Our mission: to identify the cause of the problem and quickly restore comfort .
Initial Inspection: An Aging Unit Exposed to the Elements
As soon as we arrived on the roof, the first thing we noticed was that the outdoor unit was resting on a worn and slightly sagging wooden base. Although the Gree heat pump is known for its robustness, installation on an unstable surface can cause vibrations and, over time, micro-cracks in the refrigerant pipes .
We also noted that the power supply cable showed signs of wear related to prolonged exposure to sun and rain . A visual inspection of the outdoor evaporator coil revealed slight surface oxidation, typical of unprotected rooftop installations.
Technical diagnosis: search for a refrigerant leak
Our technicians then carried out a series of tests:
-
Refrigeration circuit static pressure measurement — abnormally low result.
-
Nitrogen pressure leak test - loss detected at compressor inlet connection.
-
Compressor check — electrical coils intact, but unable to start due to insufficient pressure.
The diagnosis was clear: a micro-leak of refrigerant (R-32) was preventing the compressor from functioning properly. Without refrigerant, the heat pump can neither extract heat nor produce cold, which explains the warm airflow observed inside.
Intervention: repair, recharging and upgrading of the installation
We undertook a complete repair in several stages:
-
Brazing the leaking fitting with a high-strength alloy compatible with R-32.
-
Leak test at 350 psi for 30 minutes to confirm no leaks.
-
Deep vacuum the system to remove all traces of moisture and air.
-
Recharge with R-32 refrigerant according to Gree manufacturer's specifications.
-
Upgrade of the installation base : replacement of the wooden support with treated composite anti-vibration blocks for flat roofs.
Once the unit was restarted, we measured 100% efficiency with an indoor blowing temperature of 11°C in air conditioning mode , confirming that the refrigeration cycle was working perfectly again.
The importance of a stable and protected installation
This type of intervention highlights an often overlooked point: the quality of the outdoor unit's support directly influences the system's durability. An untreated wooden base, exposed to rain and temperature fluctuations, will eventually warp, causing vibrations and stress on the refrigeration pipes.
At AirGreen, we systematically advise our clients:
-
Opt for a composite or galvanized steel structure for roof installations.
-
To carry out an annual visual inspection of conduits and cables.
-
Consider a protective shelter (rain canopy) to extend the life of the equipment.
Result: comfort restored and energy efficiency restored
After the repair and recharge, the Gree heat pump returned to optimal operation. The owner immediately noticed improved indoor comfort and reduced outdoor noise thanks to the new anti-vibration base.
This intervention in Rosemont–La Petite-Patrie once again demonstrates AirGreen's ability to intervene effectively on complex rooftop installations , where access and exposure conditions require a rigorous technical approach.
AirGreen Expertise: Precision Serving Montreal Comfort
Our certified technicians are trained to work on all major brands of heat pumps, including Gree, Fujitsu, Midea, Sharp, Goodman, and Trane , throughout Montreal, Laval, Longueuil, on the North Shore and the South Shore .
We pride ourselves on combining in-depth diagnostics, transparency, and quality workmanship to ensure the long-term reliability and performance of each HVAC system.