An LG wall-mounted heat pump installed above a door that no longer cooled like before
In a residence in Laval, our AirGreen team was called for a HVAC service call on an LG wall-mounted heat pump, installed high above an interior door. The unit on site was a wall model from the LG Neo Plasma series, an older model but still very common in many houses and condos in the greater Montreal, Laval, Longueuil, North Shore, and South Shore areas.
The customer contacted us because the device seemed to be working but was not delivering the expected comfort. The heat pump would start, the flap would open, the ventilation would turn on, but the air blown felt less cool than before. During certain periods, especially on more humid days, the unit took much longer to cool the space. The customer also noticed a louder ventilation noise and a slight odor at startup, a common sign of internal dirt buildup or moisture stagnation in the condensate tray.
This type of situation is common with older wall-mounted heat pumps. The device may still respond to the remote control and seem to operate normally, while having lost a significant part of its efficiency. At AirGreen, we always approach this kind of intervention methodically: before discussing replacement, we need to understand what is really happening inside the unit.
An installation setup that requires precise diagnosis
The indoor unit was installed directly above a door, very close to the ceiling. This setup is common in homes where available wall space is limited. It frees up the main walls and distributes air in a passage area, but it sometimes complicates maintenance.
A device placed so high may be cleaned less often by the owner, simply because access to the filters is less convenient. Over time, dust accumulates in the filters, on the evaporator, in the ventilation turbine, and around the air blowing shutter. This buildup eventually reduces airflow and can impair cooling or heating capacity.
In this case, the LG wall unit was also relatively close to the ceiling. This detail is important: when a wall-mounted heat pump has little space above, the return air can be slightly limited, especially if the filters are already dirty. The machine then has to work harder to draw in ambient air, which can amplify noise and slow down heat exchange.
Symptoms reported by the customer
Before disassembling the device, we took the time to validate the symptoms. The customer did not describe a complete failure, but rather a gradual performance decline. This is often more subtle and sometimes more difficult to diagnose than a completely stopped device.
The main symptoms were as follows:
- the blown air seemed less cold in cooling mode;
- the airflow was weaker than before;
- the unit made a drier and less regular ventilation noise;
- a slight odor appeared at startup;
- the customer feared a condensation or drain problem;
- the requested temperature was reached much more slowly.
These clues pointed us toward a possible combination: dirty filters, dirty ventilation turbine, partially clogged evaporator, and slowed condensate drain. However, on an LG wall-mounted heat pump, it is also necessary to check the electronics, sensors, ventilation motor, and communication with the outdoor unit. A complete diagnosis prevents unnecessary part replacements.
Inspection of the LG Neo Plasma wall-mounted heat pump
The LG unit showed several typical signs of a device with several years of service. The facade was slightly yellowed over time, which is not a mechanical problem in itself, but often indicates an older machine that deserves careful inspection.
We first checked the condition of the facade, the motorized shutter, and the air blowing area. The shutter opened properly, but the airflow was not as strong as it should have been. We then removed the filters and inspected the accessible interior of the unit.
Filter check
The filters were loaded with fine dust. It was not a total blockage, but enough to reduce the quality of the air drawn in and limit the flow. On a wall-mounted heat pump, even a moderate restriction can have a significant effect, especially if the turbine and coil are also dirty.
We cleaned the filters and checked their overall condition. When a filter is damaged, deformed, or poorly repositioned, it can let more dust pass to the evaporator. In this case, the filters were salvageable, but their maintenance had not been frequent enough to maintain optimal performance.
Evaporator inspection
The indoor evaporator was partially blocked by an accumulation of dust and debris. This component is essential: it allows heat exchange between the room air and the refrigerant. When air does not properly pass through the coil, the device can produce cold but fail to distribute it effectively.
A dirty evaporator can also promote the formation of stagnant moisture and odors. In a house in Laval, as elsewhere in Greater Montreal, humid summers put a lot of pressure on wall systems. A unit in air conditioning mode not only lowers the temperature: it also dehumidifies the air. If the condensate pan and coil are dirty, moisture can leave deposits and create odors at startup.
Ventilation turbine inspection
The turbine was one of the most important elements in this diagnosis. On older wall units, the ventilation wheel can accumulate a layer of sticky dust. This layer changes the shape of the blades and reduces the turbine's ability to push air.
The client specifically described low airflow and a louder noise. These two symptoms very often correspond to a dirty turbine. A ventilation motor can be perfectly functional, but if the wheel is dirty, the device seems tired. This is an important distinction in an HVAC repair: the problem is not always electrical or mechanical; it can be related to the internal condition of the unit.
Drainage and condensate diagnosis
Since the unit was installed above a door, any water leak could have caused visible damage to the frame, paint, or floor. We therefore inspected the condensate pan and tested the drain flow.
The drain was not completely blocked, but the flow was slower than desired. A slow drain may work during a short test but overflow after several hours of cooling in humid weather. This often explains intermittent leaks: the customer does not see water every day but sometimes notices traces after a period of high humidity.
We cleaned the condensate passage and confirmed that the water was draining properly. This step is essential because an internal leak is one of the most unpleasant problems with a wall-mounted heat pump. It can be caused by a blocked drain, improper slope, a dirty pan, an uneven installation, or significant buildup on the evaporator.
Verification of refrigeration operation
After internal checks, we tested the device’s operation in cooling mode. We observed the return air temperature, the supply air temperature, the outdoor compressor’s response, and the stability of the operation.
The temperature difference indicated that the system was still producing cold air, but distribution was compromised by the internal condition of the wall unit. In other words, the LG heat pump was not necessarily at the end of its life; it mainly needed targeted refurbishment to regain better efficiency.
In several service calls in Montreal, Laval, Longueuil, on the North Shore and the South Shore, we see similar situations: customers think the compressor is weak or that refrigerant is low, while the primary problem is often the airflow. Therefore, it is important to avoid quickly concluding that there is a refrigerant leak or that a full replacement is needed.
The AirGreen intervention: internal cleaning and recommissioning
Once the diagnosis was made, we carried out a complete intervention on the indoor unit. The goal was to restore airflow, improve heat exchange, and secure condensate drainage.
Work area protection
Since the device was installed above a door and near a finished wall, we protected the area before cleaning. Service on a wall-mounted heat pump must be clean and controlled. Internal residues can dirty walls or drip onto surfaces if the intervention is done without proper method.
Cleaning internal components
We cleaned the filters, the return air area, the accessible evaporator, the fan, and the air flap. Cleaning the fan had an immediate effect on airflow quality. When this part is clogged, the device often loses much of its ventilation capacity, even if the motor is still running.
Cleaning the evaporator also improved heat exchange. A cleaner coil allows air to circulate more easily and helps the device cool more efficiently.
Drain cleaning and testing
We then cleaned the drain and tested the flow. Water passage was smoother after the intervention. This validation was important to reassure the client, especially with a unit placed above an indoor passage.
Final performance test
Once the device was reassembled, we performed a complete test. The flap responded correctly, the ventilation was more even, the noise was reduced, and the blown air was more consistent. The machine no longer gave the impression of working “halfway.” The client quickly noticed an improvement in comfort in the serviced area.
Comfort restored without unnecessary device replacement
The result of this service call confirmed the importance of a structured diagnosis. The LG wall-mounted heat pump still had a valid operating capacity. The main problem was internal clogging, reduced airflow, and drainage that was starting to slow down.
In this kind of case, replacing the device immediately would have been premature. Professional service can sometimes extend the life of a machine, improve comfort, and reduce the risk of future problems. Of course, when a device is very old, you also need to monitor the condition of the compressor, electronic boards, fan motor, and the availability of parts. But here, the best decision was first to restore the unit to proper working condition.
Why older LG wall-mounted heat pumps require special attention
LG Neo Plasma units have been installed in many homes over the years. Many still work, but they often require more thorough maintenance, especially if they haven’t been deeply cleaned for a long time.
With age, some components become more sensitive:
The fan can become noisy
Accumulated dust can unbalance the fan wheel. This sometimes creates rubbing noises, vibrations, or irregular airflow sounds.
The drain can clog more easily
Deposits in the tray and drain can slow water evacuation. In summer, high humidity can quickly turn a partially clogged drain into an indoor leak.
Sensors may misread the temperature
If air does not circulate well around the unit or if the interior is dirty, the sensor may interpret the temperature less accurately. The device may then stop too early or run longer than necessary.
The evaporator loses efficiency
A dirty coil reduces the device’s ability to transfer heat. The machine has to work longer to produce the same result.
Mistakes to avoid before calling a technician
A customer can perform some simple actions, but certain common mistakes should be avoided.
You should not spray just any product inside the unit. Some cleaners can damage plastics, electronic components, or leave irritating residues. You should also not disassemble the front panel or force the motorized flap without knowing the device’s structure.
It is also risky to ignore a small leak. An occasional drop can signal a slow drain or a tray that is starting to clog. Waiting for water to flow abundantly can lead to damage to walls or framing.
Finally, you should not automatically conclude that the device is low on refrigerant. A lack of cooling can come from the refrigerant, but it can also be caused by low airflow, a dirty coil, a clogged fan, or poor circulation in the room.
Our recommendations after this HVAC repair
After the intervention, we advised the client to clean the filters regularly and schedule periodic HVAC maintenance, especially if the device is used as much for cooling as for heating. A wall unit installed above a door can work very well, but it must stay clean to properly draw in and distribute air.
We also recommended monitoring the following signs:
- gradual decrease in airflow;
- louder fan noise;
- smell at startup;
- water traces near the unit;
- slower cooling;
- unusual shutdown or restart;
- visible dust buildup in the air outlet.
These signs do not always mean a major repair is necessary, but they indicate that a diagnosis is useful.
AirGreen, specialist in residential HVAC service calls
This service call on a wall-mounted LG heat pump in Laval is exactly the type of intervention where experience makes the difference. A wall unit can have several possible causes for the same symptom. The technician’s role is not just to note that the device is cooling less; they must identify why.
At AirGreen, we work on wall-mounted heat pumps, wall air conditioners, MultiZone heat pumps, central heat pumps, electric furnaces, and residential systems in the greater Montreal, Laval, Longueuil, North Shore, and South Shore areas. Our approach is based on a thorough inspection, clear explanation, and intervention tailored to the actual condition of the device.
In this case, the solution was concrete: internal cleaning, drainage check, airflow validation, and putting the system back into service. Comfort was restored, performance improved, and the client was able to continue using their device with more confidence.