A well-installed heat pump... but poorly positioned
During this service call in Rosemont–La Petite-Patrie , our AirGreen team was asked to work on an LG wall-mounted heat pump that was showing symptoms of compressor overheating and unexpected shutdowns during a heatwave.
The customer, aware of the importance of regular maintenance, had already cleaned the internal filters. However, despite his precautions, the system continued to automatically shut off after a few minutes of operation.
Upon our arrival on site, one detail immediately caught our attention: the outdoor condenser was installed in a very narrow space , wedged between two brick walls and partially above a staircase leading to the basement. A position that, at first glance, might have seemed practical and discreet... but which posed a major ventilation problem.
Diagnosis: lack of ventilation and compressor overheating
Our technicians carried out a series of systematic checks:
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Compressor discharge temperature , recorded at 68°C after barely 10 minutes of operation.
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R-410A refrigerant pressures , which indicated stress operation.
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Fan speed , stable, but inefficient due to the air being recycled in the confined space.
The verdict was clear: the heat pump lacked fresh air to dissipate the heat produced . In such a narrow cavity, the condenser rejects hot air that is immediately sucked back in, resulting in a long-term thermal loop that is fatal for the compressor.
Step 1: Complete cleaning and effectiveness testing
Before any structural modifications, we carried out a complete cleaning of the external exchanger using a biodegradable product specific to HVAC coils.
We then let the system run for 15 minutes to measure the impact of cleaning alone: performance had improved, but the compressor temperature remained too high (around 60°C).
It was necessary to go further.
Step 2: Strategic repositioning of the condenser
In consultation with the owner, we proposed relocating the condenser to a more exposed wall mount, allowing better air circulation vertically and laterally.
This intervention included:
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Complete recovery of R-410A refrigerant using a certified recovery cylinder.
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Moving and fixing the condenser to a more open position, 45 cm from the wall and clear of stairs.
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Replacement of the suction hose and new insulation of the refrigeration pipe.
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A calibrated refrigerant recharge according to the exact pipe length, measured after repositioning.
This step eliminated the root cause of overheating and restored optimal airflow around the unit.
Step 3: Post-intervention performance verification
After the restart, the new measurements revealed:
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Pressure balanced at 120/415 psi , perfectly in line with LG specifications.
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Compressor temperature stabilized at 47°C .
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Air blown at 16°C at the outlet of the indoor unit , demonstrating restored thermal efficiency.
The customer immediately noticed that the heat pump operated more quietly and without any untimely shutdowns.
Step 4: Maintenance and prevention tips
We took advantage of this visit to share several practical recommendations:
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Always maintain a minimum clearance of 30 to 40 cm around the condenser.
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Avoid installing the unit in enclosed or recessed areas such as stairwells.
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Clean outdoor coils in spring and fall.
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Carry out a complete annual maintenance including gas and drainage check.
These simple actions help ensure increased compressor longevity and optimal energy efficiency .
AirGreen: Local expertise in LG heat pump repair in Montreal
This type of situation perfectly illustrates the realities of residential buildings in Montreal, where limited space can hamper the proper functioning of an HVAC system . At AirGreen, we know how to adapt our interventions to architectural constraints while guaranteeing the performance and reliability of the equipment.
Our certified technicians operate throughout Montreal, Laval, Longueuil, the North Shore and the South Shore to diagnose, repair and optimize all models of wall-mounted heat pumps — LG, Fujitsu, Sharp, Gree, Midea, Trane and more .
In summary:
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Initial problem: unscheduled shutdowns caused by overheating.
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Cause: Poor air circulation due to an incorrectly positioned condenser.
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Solution: Complete cleaning, repositioning and recharging of the refrigerant.
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Result: stable operation, restored energy efficiency and reduced noise.
AirGreen – LG wall-mounted heat pump experts in Rosemont–La Petite-Patrie and throughout Greater Montreal.