Air conditioning failure in a room in the summer heat
When a wall-mounted air conditioner stops cooling effectively, the comfort of a room can quickly deteriorate. This is exactly what happened to a customer in Saint-Lambert , on the South Shore of Montreal , who contacted us for an urgent service call regarding a Gree wall-mounted air conditioner installed in a master bedroom.
The unit, which looked new, was no longer blowing cold air despite a normal display and audible operation of the interior fan. At AirGreen , we know that such a symptom can have several causes: a refrigerant leak, a problem with the electronic board, or a blocked evaporator coil.
Accurate and rapid diagnosis: the crucial role of the temperature sensor
Upon our arrival, our technicians carried out a series of functional and electrical checks :
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The indoor unit responded correctly to commands.
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The fan was running at all speeds.
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No errors were displayed on the screen.
However, the temperature of the blown air remained almost identical to that of the room.
Further analysis revealed that the evaporator temperature sensor (thermistor) was no longer transmitting the correct reading to the main board. As a result, the board believed the target temperature had been reached and was preventing the outdoor compressor from starting.
A resistance test of the sensor confirmed the fault: its ohmic value no longer varied according to the ambient temperature.
AirGreen intervention: sensor replacement and complete restart
Once the cause was identified, our team undertook a meticulous repair :
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Partial disassembly of the Gree wall unit housing to access the faulty thermistor.
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Replacement of the temperature sensor with an original Gree part, guaranteeing compatibility and reading accuracy.
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Checked the main control board to ensure no overvoltage or corrosion was present.
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Complete cleaning of the evaporator coil and air filters, often neglected yet essential for energy efficiency.
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System reboot and full performance test : within minutes, the exhaust air temperature dropped to 9°C — proof of effective cooling.
The whole thing was done in less than 90 minutes, without any major interruption for the customer.
Results: restored comfort and optimal performance
Thanks to this intervention, the room temperature has returned to ideal comfort and the Gree wall-mounted air conditioner now works like new.
The customer was particularly satisfied with our accurate diagnosis , avoiding unnecessary replacement of the system.
Our technicians also took care to reorganize the connection cables inside the hood, to avoid any friction or mechanical tension that could damage the sensor wires in the long term.
AirGreen Tips: Preventing Common Wall-Mounted Air Conditioner Breakdowns
Gree systems, like many other reputable brands, offer excellent durability when properly maintained. Here are some practical recommendations to avoid similar breakdowns:
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Clean filters every 4 to 6 weeks during the summer season.
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Have sensors and connections inspected at least once a year.
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Ensure that the indicator lights and operating mode are correct before each use.
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Avoid covering the unit with curtains or objects, which disrupt air circulation.
Annual preventive maintenance performed by our AirGreen technicians can prevent up to 70% of electrical failures on wall systems.
AirGreen Expertise: Fast and Professional Service Across Greater Montreal
This Gree wall-mounted air conditioner repair in Saint-Lambert perfectly illustrates our approach: a targeted, rapid and lasting intervention , always with original parts and methods that comply with the manufacturer's standards.
At AirGreen , we serve Montreal, Laval, Longueuil, the North Shore and the South Shore , and we work on all recognized brands: Gree, Fujitsu, Sharp, Midea, Bosch, Lennox, Trane, Goodman , and many others.
Our goal remains the same: to restore your comfort as quickly as possible while ensuring the reliability of your HVAC system for years to come.