A quick service call to restore comfort to an overheated stairwell
At AirGreen , our technicians are often called upon to work in areas where thermal comfort is difficult to maintain—particularly open-plan stairwells. Recently, we were contacted by a client in Sainte-Dorothée, Laval, whose Mitsubishi wall-mounted air conditioner was no longer properly cooling the upper landing area, creating a temperature imbalance between floors.
The diagnosis: a dirty device and a faulty temperature probe
Upon our arrival, we conducted a thorough inspection of the wall unit installed above the stairs. This Mitsubishi model was part of a typical residential installation, ensuring the comfort of the mezzanine and the bedrooms upstairs.
Here is what we observed:
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The air filter was heavily clogged with dust —a common cause of loss of efficiency.
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The indoor temperature sensor was sending inconsistent values to the control board, preventing the outdoor compressor from firing.
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The unit made a slight clicking noise , indicating an unbalanced interior fan.
These symptoms explained the persistent feeling of heat upstairs, despite a thermostat set at 21°C.
Technical intervention: deep cleaning and probe replacement
After validation with the customer, our technician undertook the following steps:
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Complete cleaning of the front panel, filters, turbine and evaporator using a no-rinse antibacterial product.
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Replacement of the interior temperature sensor , responsible for the poor signal return to the main board.
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Rebalanced the fan to eliminate slight vibrations that could reduce motor life.
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Communication test between the indoor and outdoor units to ensure proper compressor operation.
Once the work was completed, the unit was tested in cooling mode: the airflow became constant, powerful and, above all, perfectly directed towards the landing.
Result: restored comfort and optimal performance
As soon as the intervention was over, the difference was noticeable:
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The temperature of the floor stabilized in less than 20 minutes.
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The device operated quietly, at nominal power.
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The client noted a marked improvement in overall comfort in the upstairs bedrooms.
We also recommended annual preventative maintenance to prevent this type of problem from recurring, especially before the summer season.
Why this repair was important
In an open-floor home, a wall unit failure can quickly cause a thermal imbalance that is difficult to correct. By intervening quickly, we were able to:
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An immediate reduction in energy consumption.
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An improvement in overall thermal comfort.
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Extending the life of the Mitsubishi device.
Our commitment to Laval and the North Shore
AirGreen is proudly located in the Laval region, and we respond to service calls every day for all types of residential and commercial HVAC systems . Whether it's a Mitsubishi air conditioner, a Fujitsu heat pump, or a Midea multi-zone system, our team is trained to respond quickly, diagnose accurately, and restore the comfort of your home.
In summary:
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Device Type: Wall-mounted Air Conditioner
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Brand: Mitsubishi
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Location: Sainte-Dorothée, Laval
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Problem: Ineffective cooling, faulty temperature sensor
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Solution: Complete cleaning, probe replacement, functional test
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Result: Comfort restored, efficient and silent device
At AirGreen, we believe that a well-maintained HVAC system means lasting comfort, optimal energy efficiency, and guaranteed peace of mind.