Rapid intervention and complete restoration of comfort in a condo in downtown Montreal
At AirGreen , we know that wall-mounted air conditioning systems are essential to the comfort of downtown residents, especially during Montreal's hot and humid summers. In this case, our team intervened in a condo in the Ville-Marie district , where an LG wall-mounted air conditioner installed on a small red brick balcony was showing signs of failure.
📍 Context of the intervention
The customer contacted us after noticing that their air conditioner was no longer producing cold air despite the operating indicator light being on. The outdoor unit, a single-zone LG model placed on a wooden balcony floor, appeared clean and undamaged, but no efficient heat exchange was taking place.
Since the LG system is known for its reliability and inverter technology, our technician immediately suspected a communication problem between the outdoor electronic board and the wall unit .
🧰 Diagnostics and technical checks
1. Signal and supply voltage analysis
The first test consisted of checking the supply voltage (240 V) and the communication between the boards. The measured voltage was stable, but the control signal showed a cyclical interruption every 10 seconds , indicating an internal fault in the external board.
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Input voltage : 240 V AC — compliant
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Control signal : irregular fluctuation (oscillation between 4.5 and 6 V DC)
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Error code displayed : CH05 – Communication interrupted
2. Inspection of the external electronic board
After opening the protective case, our technician identified advanced oxidation on the low-voltage connectors due to prolonged exposure to moisture. This corrosion was preventing stable signal transmission between the two units.
So we have:
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Cleaned the connectors with a specialized dielectric degreaser .
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Replaced the oxidized terminals .
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Applied an insulating varnish to prevent future infiltration.
3. Checking the compressor and refrigerant
Once communication was reestablished, the compressor restarted, but the operating pressure was below LG specifications .
We then checked the R410A refrigerant level . A slight leak was detected at the flare connection of the suction line.
The intervention consisted of:
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Tighten the fitting with a calibrated torque wrench.
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Perform a nitrogen leak test at 400 psi for 30 minutes.
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Carry out a complete vacuum draw then a recharge of 850 g of R410A .
⚙️ Performance tests after repair
Once the recharge was complete, the system was tested for a full cycle:
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Blown air temperature : 11°C at outlet (ambient air at 26°C).
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Condensing pressure : 375 psi.
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Compressor noise : stable and vibration-free.
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Power consumption : in accordance with nominal values.
The air conditioner has regained its full cooling capacity and is now operating with optimal energy efficiency .
🌡️ Technical challenges of the intervention
The main challenge of this intervention came from the limited space of the balcony , making it difficult to safely handle the refrigerant and tools. In addition, the lack of shelter above the unit exposed the electronic board to the elements—a common problem in high-rise urban installations.
Our technicians used a compact intervention kit and applied additional sealing protections around the cables passing through the brick to extend the durability of the system.
💡 AirGreen Maintenance Recommendations
To ensure the longevity of the LG wall-mounted air conditioner, we advised the customer:
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Install a small rain shelter above the outdoor unit.
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Clean the internal filters regularly (at least every 2 months).
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Have the circuit pressures checked every 18 to 24 months.
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Avoid plugging other appliances into the same electrical circuit.
We also enrolled this customer in our AirGreen preventative maintenance program , which includes a complete annual inspection of the HVAC system.
🧾 Final result
Thanks to this intervention, the condo's LG wall-mounted air conditioner returned to optimal operation, ensuring rapid, quiet, and stable cooling . The client immediately felt the difference, with fresher indoor air and reduced energy consumption.
At AirGreen , we combine technical expertise, diagnostic accuracy, and attention to detail for every HVAC repair in Montreal , whether it's an LG, Gree, Fujitsu, or Midea wall-mounted system. Every repair is carried out according to the highest standards of performance and safety.
AirGreen Air Conditioning & Heating — HVAC system experts in Montreal, Laval, Longueuil, North Shore and South Shore.