Roofing intervention: a typical Montreal service call
At AirGreen , we are often called upon to work on wall-mounted heat pumps installed on flat roofs , a common configuration in modern buildings in Saint-Laurent . This type of installation, while practical for freeing up floor space, exposes the equipment to extreme conditions: sun, wind, rain and temperature variations.
During this service call, our team was tasked with diagnosing an LG wall-mounted heat pump that was no longer effectively cooling the units it served. The customer had noticed that the outdoor unit was working, but the indoor air remained lukewarm, even at full power.
Diagnosis: an insulation problem and loss of refrigeration pressure
Our technician began the intervention with a thorough visual inspection. The LG compressor, installed on treated wood roof supports , showed apparent mechanical integrity. However, one important detail immediately caught our attention:
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The refrigeration lines were poorly insulated and exposed to UV rays.
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Several sections of the insulation were split, exposing bare copper.
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A slight trace of oil was visible at one fitting, a potential sign of a slow leak.
These two factors combined (leakage and poor insulation) perfectly explained the loss of performance observed by the customer.
Step 1: Pressure Test and Leak Detection
Using a pressure gauge and an electronic detector, we confirmed a microleak at the flare joint of the liquid line . The original joint had deteriorated, probably due to the extreme thermal cycles experienced by the rooftop installation.
After bleeding the circuit, we replaced the defective seal and tightened the connection to the tightening torque recommended by LG , ensuring optimal sealing.
Step 2: Complete renovation of the insulation of the refrigeration lines
To prevent the problem from recurring, we undertook a complete overhaul of the copper pipe insulation :
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Removing damaged sections of insulation.
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Application of a high-density, UV- and heat-resistant foam sheath .
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Sealed with aluminized tape to maximize durability.
This step is essential on exposed roofs, as damaged insulation causes efficiency losses of up to 20% in system performance .
Step 3: Refrigerant recharge and final calibration
Once the seal was restored, we carried out a complete recharge with R-410A , respecting the manufacturer's specifications. Precise measurements confirmed the return to a stable and compliant pressure.
Results after intervention:
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Blowing temperature: 10.8°C (compared to 18°C before repair).
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Balanced pressure between the liquid and gas lines.
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Noise level reduced by 15%.
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Standardized power consumption.
AirGreen Prevention and Recommendations
We advised the customer on several measures to preserve the longevity of his LG heat pump :
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Annual inspection of refrigeration lines , particularly the condition of the insulation.
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Clean the condenser twice a year.
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Applying a protective coating to the roof around the support to prevent water accumulation.
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Install a UV shield if exposure to direct sunlight is present all day.
These simple precautions can significantly extend the lifespan of rooftop systems, while maintaining optimal energy efficiency.
AirGreen expertise: rigor, precision and reliability
Each service call is an opportunity for us to demonstrate the rigor and precision that AirGreen is known for throughout Greater Montreal, Laval, the North Shore and the South Shore.
Our technicians are trained to work on all major brands— LG, Fujitsu, Gree, Napoleon, Sharp, Midea, Bosch, Trane —and use modern diagnostic tools to ensure long-lasting repairs that meet manufacturer standards.
Result: comfort restored and performance restored
Thanks to our intervention, the LG heat pump in Saint-Laurent is now operating at full capacity. The client has regained optimal comfort, even on the hottest days.
This type of case perfectly illustrates the importance of regular professional maintenance , especially for rooftop systems. At AirGreen, we ensure that every installation—whether residential or commercial—operates at its full potential, summer and winter.