An LG wall unit that cooled less, leaked slightly, and required a real HVAC diagnosis
In Sainte-Marthe-sur-le-Lac, on the North Shore, our AirGreen team was called for a LG wall-mounted heat pump repair installed above a large patio door leading to the backyard. The device, an indoor LG Inverter V wall type unit, was mainly used to cool the main living area during hot days, while providing supplemental heating during intermediate seasons. The customer contacted us after noticing three specific symptoms: a gradual drop in performance, an unusual flow noise, and small traces of moisture under the unit.
At first glance, the installation seemed clean: the wall unit was well positioned high up, centered above the glass opening, with enough clearance to distribute air in the room. However, this type of location, very common in homes in Sainte-Marthe-sur-le-Lac, Laval, Montreal, Longueuil, on the North Shore and the South Shore, requires special attention. A patio door lets in a lot of solar heat, especially in the afternoon. If the indoor unit is dirty, if the condensate drain is partially blocked, or if the tangential fan loses efficiency, comfort quickly drops.
Our intervention was therefore not just about “getting” the device to work again. We needed to understand why this LG wall-mounted heat pump was no longer delivering its usual performance and why the condensation water was no longer draining properly.
Symptoms observed before the service call
The customer explained to us that the unit was still working, but it was taking much longer than before to cool the room. Even when lowering the setting on the wall thermostat or with the remote control, the air blown seemed less cold, and the airflow appeared irregular. After long periods of operation, a thin trace of moisture sometimes appeared under the right side of the unit.
These signs often point the diagnosis toward several possible causes:
- filters saturated with dust;
- dirty indoor coil;
- partially blocked condensate drain;
- insufficient slope or sagging of the drain pipe;
- dirty or unbalanced tangential fan;
- temperature sensor poorly influenced by the environment;
- refrigerant level to check if performance remains low after cleaning;
- electronic board or louver motor to check if air distribution is abnormal.
In this specific case, the LG unit did not show a total failure. It rather showed signs of loss of efficiency, typical of a system that needs a serious HVAC diagnosis before the problem becomes more costly.
Visual inspection of the LG wall unit
Upon arrival, we inspected the indoor unit. The device was installed very close to the ceiling, which is common in rooms where air diffusion is maximized. The front bore the LG logo and the Inverter V label, confirming it was a wall system with inverter technology. The full nameplate was not readable in the provided photo, but the unit’s size corresponded to a common residential capacity, generally used for an open area or main room.
We started by checking:
- the condition of the filters;
- the cleanliness of the evaporator;
- the rotation of the indoor fan;
- the operation of the louvers;
- the presence of moisture in the condensate tray;
- the drain evacuation;
- the blowing temperature;
- the unit’s response to controls;
- the stability of the cooling cycle.
The filters were loaded with fine dust. This dust is not always visible from afar, but it forms a barrier that reduces air flow. On a wall-mounted heat pump, a clogged filter can cause a series of effects: reduced flow, less effective cooling, excessive condensation on the coil, slower drainage in the tray, and general discomfort in the room.
Condensate drainage diagnosis
The moisture problem under the unit led us to pay special attention to the drainage system. In cooling mode, the indoor unit removes moisture from the air. This water must accumulate in the condensate tray, then drain out through a pipe. If this drain is partially blocked, the water can stay too long in the tray, cause a flowing noise, emit a slight odor, or eventually leak inside.
Our technician tested the flow by pouring a small amount of water into the tray in a controlled way. The water drained, but too slowly. This detail was important: a completely clogged drain would have caused a larger leak. Here, it was more of a partial blockage, probably caused by a mix of dust, biofilm, and deposits accumulated over the seasons.
We then inspected the accessible path of the drain and checked that the unit was still properly leveled. A slight deformation of a support or accumulation in the tray can be enough to slow drainage, especially when the unit runs for a long time during a humid period.
Technical cleaning: filters, evaporator, tray, and drain
The repair began with a methodical cleaning. We removed the filters, cleaned accessible surfaces, and treated the condensate tray area. The goal was to restore airflow and allow water to drain without stagnation.
Our intervention included:
- cleaning the filters of the wall unit;
- inspection of the evaporator fins;
- cleaning accessible areas of the indoor coil;
- clearing the condensate tray;
- unclogging the drain;
- checking the evacuation flow;
- cleaning the air outlet;
- checking the operation of the tangential fan;
- complete test in cooling mode.
In several cases of wall air conditioner repair or wall-mounted heat pump, this combination of cleaning and drainage correction is enough to solve the problem. However, at AirGreen, we don’t stop at a quick improvement. We always confirm the result with operational tests.
Performance check after intervention
After cleaning and clearing the drain, we restarted the LG wall-mounted heat pump. The device was tested in cooling mode, with a low enough demand to force a stable cycle. The airflow was more uniform and the blowing temperature improved after a few minutes of operation.
We also checked that the condensation water was draining properly. This step is essential: a drain may seem unclogged for a few seconds but become problematic again if the flow is not strong enough. In this case, the flow had returned to normal, with no visible stagnation in the tray and no water traces under the unit.
The flow noise reported by the customer has also decreased. This type of noise often comes from water accumulation in the tray or a partially blocked passage. Once the drain is cleared, the water drains more naturally and the unit operates more quietly.
Why this failure is common in a room with a patio door
The location of the unit above a large patio door is convenient for distributing air in the living area, but it also exposes the device to demanding conditions. Solar heat, humidity entering when the door is open, dust from the backyard, and rapid temperature changes increase the workload of the wall heat pump.
In this residence in Sainte-Marthe-sur-le-Lac, the LG unit had to handle a bright area open to the outside, with a high thermal load in summer. When the filters and coil start to get dirty, the system has to run longer to reach the same temperature. The longer it runs, the more condensate it produces. If the drain is already slowed, the risk of leakage increases.
That is why we recommend more regular preventive maintenance for wall units installed:
- above a patio door;
- in a kitchen or near a cooking area;
- in a very sunny room;
- in a house with pets;
- near a zone where doors are often open;
- in a heavily used living area.
Mistakes to avoid with an LG wall heat pump
Waiting for a leak to become significant
A small trace of water under a wall unit should never be ignored. Even if the device continues to cool, moisture can damage the wall, framing, paint, or floor. A quick intervention often prevents secondary repairs.
Cleaning only the filters
Cleaning the filters is important, but it does not always solve problems with the tray, drain, or evaporator. A unit can have clean filters and still leak if the drain is clogged further down.
Using unsuitable products
Some household products can leave residues, emit odors, or damage internal components. For an HVAC repair, it is necessary to use methods compatible with wall-mounted equipment and respect the nearby electrical components.
Forcing the louvers manually
The louvers of an LG wall unit are motorized. Forcing them by hand can damage the mechanism or cause an airflow distribution problem. When a louver seems stuck, it’s best to have the motor, alignment, and controls checked.
What the client noticed after our visit
Once the repair was completed, the client quickly noticed a difference. The air was better distributed, the unit operated more smoothly, and humidity no longer accumulated under the device. The room began to cool more steadily without having to excessively lower the thermostat setting.
We also took the time to explain the steps to take after the intervention: monitor for water appearance, clean the filters regularly, and have the unit serviced before periods of intense heat. In a home located on the North Shore, where the seasons require both cooling and supplemental heating, a well-maintained wall heat pump remains a very useful piece of equipment.
A precise HVAC repair to extend the lifespan of a wall unit
This intervention in Sainte-Marthe-sur-le-Lac clearly shows that a LG wall heat pump repair is not just about replacing a part. In this case, the problem was mainly due to a combination of dirt buildup, slow drainage, and reduced airflow. A misinterpretation could have led to an unnecessary replacement of more expensive components.
At AirGreen, we prioritize a thorough diagnosis before drawing any conclusions. We observe the actual behavior of the device, test the essential functions, check common causes, and validate the result after the intervention. This approach allows us to offer reliable service in Montreal, Laval, Longueuil, on the North Shore and the South Shore, for wall-mounted heat pumps as well as wall air conditioners, multi-zone systems, central heat pumps, and other residential HVAC equipment.
Our recommendations after this type of repair
To maintain good performance, we recommended the client to:
- clean the filters every few weeks during intensive use periods;
- watch for signs of moisture under the unit;
- avoid blocking air diffusion with curtains too close to the unit;
- have the drain checked if water noise returns;
- schedule a full maintenance before the hot season;
- do not wait for a complete breakdown before requesting service.
In this room, the curtains and proximity to the patio door also required special attention. Even if the unit’s installation was functional, air circulation must remain free to allow the system to properly mix the room’s air. A curtain too close or constantly pushed toward the unit can disrupt airflow and affect the temperature sensor.
A service adapted to the realities of homes on the North Shore
Homes in Sainte-Marthe-sur-le-Lac and surrounding areas often have varied layouts: large windows, open areas, finished basements, extensions, sunrooms, patio doors, and sun-exposed rooms. A wall-mounted heat pump must therefore be evaluated in its real context. The same unit can work perfectly in one room and be more stressed in another.
This is exactly what we considered during this service call. The LG unit was not simply “dirty” or “defective.” It was operating in a bright space, with higher humidity and heat load, and its drainage system had eventually lost effectiveness. By fixing the cause rather than masking the symptom, we restored comfort and reduced the risk of recurrence.
For AirGreen, a good HVAC repair must be durable, understandable, and adapted to the building. This service in Sainte-Marthe-sur-le-Lac is a concrete example: structured diagnosis, targeted cleaning, cleared drain, verified performance, and reassured customer.