An overheating outdoor compressor on an urban terrace
At AirGreen , our interventions in Montreal's dense neighborhoods, such as Côte-des-Neiges–Notre-Dame-de-Grâce , often require a specific technical and logistical approach. During this service call, the owner of a condo located on the top floor of a modern building contacted us about an LG wall-mounted heat pump installed on his private terrace. The system was no longer able to adequately cool the living room despite the constant compressor noise.
Initial diagnosis: condenser overheating and abnormal pressure
Upon arrival, the LG outdoor unit was sitting on a wooden deck in direct sunlight without any shelter or shade. The ambient temperature was over 30°C, and the customer noticed that the system was running continuously without ever reaching the setpoint.
Our initial measurements revealed:
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High refrigerant pressure in cooling mode,
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Warm air blown inside despite a running compressor,
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Condenser clogged with fine dust and oily deposits.
This type of situation is common in balcony or flat roof installations in Montreal: the outdoor units are subject to more reflected heat and dirt than those installed on the ground.
Step 1: Complete inspection of the LG heat pump
Before any intervention, we checked the condition of the electrical wiring, the refrigeration connections and the condensate line . Everything was well sealed, no signs of leaks.
However, the outside temperature sensor showed a reading offset of nearly 4°C from reality – a factor that could unbalance the compressor control logic.
We also found that the insulated conduit connecting the wall unit to the outside was poorly protected from the sun: the black insulation, cracked by UV rays, exposed the copper to direct heat, thus reducing the energy performance of the refrigeration cycle.
Step 2: Complete cleaning of the condenser
After turning off the power, our technician thoroughly cleaned the condenser coil using a mild alkaline cleaner and a low-pressure rinse.
This operation allows you to eliminate:
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urban dust accumulated between the fins,
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fine fats due to air pollution,
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and organic micro-debris blocking airflow.
Once dried, the airflow through the exchanger returned to an optimal level, lowering the pressure in the refrigeration circuit significantly.
Step 3: Partial replacement of the cold insulation
We then replaced the deteriorated section of copper pipe insulation and added a white UV resistant jacket .
This simple but crucial action protects the refrigeration line from external overheating and improves performance consistency, particularly during the summer.
Step 4: Recalibration and Performance Testing
Once the maintenance and insulation correction were complete, we reset the control board and ran the heat pump in test mode.
The results were immediate:
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Air blown at 6.9°C at the interior outlet,
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Discharge pressure returned to LG specifications,
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Noise level reduced by almost 30% , proof of normal compressor workload.
The client immediately felt the difference: in less than ten minutes, the main room was back to optimal comfort.
Technical analysis: the challenges of balcony wall units
Heat pump installations on terraces, balconies or flat roofs present specific challenges:
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Heat buildup due to reflection from wood or concrete,
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Limited airflow around the condenser,
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Direct exposure to weather and UV radiation,
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Vibrations amplified by light structures.
To remedy this, AirGreen systematically recommends:
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Adding a sunshade or ventilated shelter ,
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A biannual cleaning of the condenser,
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An annual check of the refrigerant pressure ,
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Periodic replacement of external insulating sheaths .
Final result: a high-performance and durable LG heat pump
Thanks to this intervention, the LG wall-mounted heat pump has regained stable and quiet operation.
The delighted customer also decided to add their annual maintenance to our AirGreen preventative maintenance program, ensuring optimal performance throughout the year.
AirGreen: your HVAC expert in Montreal and on the South and North Shores
Our qualified technicians work every day in Montreal, Laval, Longueuil, the North Shore and the South Shore for repairs and maintenance on all major brands — LG, Fujitsu, Midea, Gree, Lennox, Trane, Goodman, and many others .
Each intervention is carried out with rigor, precision and attention to detail, because a well-maintained HVAC system means, above all, lasting comfort and reduced consumption .
AirGreen — Air conditioning and heat pump experts in Montreal, Laval, Longueuil, North Shore and South Shore.