When performance suddenly drops: a fault diagnosed with precision
At AirGreen , we know that a Midea wall-mounted air conditioner is designed to provide consistent, quiet comfort, especially on hot South Shore days. But even the most reliable systems can experience technical issues over time. This is exactly what happened during a service call in Saint-Constant , where a customer contacted us about a sudden lack of cooling in their Midea wall-mounted unit.
Diagnosis: Active display, but inoperative unit
Upon arrival, our technician immediately noticed that the wall unit was displaying a setpoint temperature of 30°C , indicating that the control electronics were working, but that the compressor was not starting . The housing was open, revealing the main circuit board and electrical connections —an indication that the customer had attempted a manual restart before calling us.
A quick visual examination revealed:
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No apparent refrigerant leaks (no traces of oil or ice).
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Stable power supply measured at the input terminal.
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Correct control signal between the main board and the communication board.
It was the main control board that caught our attention: some components showed slight oxidation around the relays. After extensive testing, we confirmed that the compressor relay was no longer closing properly, preventing the engine from starting.
Intervention: replacement of the electronic card and complete restart
We completely replaced the main control board with a genuine Midea part, supplied directly from our AirGreen stock. After installation:
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Communication between the indoor unit and the outdoor compressor was restored instantly .
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The compressor started after a 2-minute delay, and the blowing temperature quickly dropped to 9°C.
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Power consumption has returned to normal, indicating a stable cooling cycle.
We also cleaned the evaporator coil (visible in the photo) to ensure optimal airflow and extend the life of the system.
Result: comfort restored and reliability assured
In less than two hours, the customer's Midea wall-mounted air conditioner was fully operational. The home's ambient temperature returned to its original comfort level, and the customer particularly appreciated our team's transparent diagnosis and rapid response .
What this intervention illustrates
This case demonstrates the importance of having a repair performed by a certified technician . A faulty control board can sometimes appear to be a major problem (like a burnt-out compressor), but an accurate diagnosis can prevent unnecessary expenses.
At AirGreen , we regularly work on Midea units , which are renowned for their efficiency and environmentally friendly R-32 technology. Our team has a thorough understanding of their control circuits and startup sequences, allowing us to quickly identify the source of faults, whether it is:
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of a faulty relay ,
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of an incorrect temperature sensor ,
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of a communication problem between cards ,
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or a software blockage in the indoor module.
Recommended preventive maintenance
To avoid this type of incident, we recommend:
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A complete annual maintenance , including cleaning of the coil, fan and condensate tray.
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An inspection of the electrical connections , as moisture can cause slow oxidation.
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A check that the probes and relays are working properly .
Preventive maintenance performed by AirGreen not only ensures the long-lasting performance of your Midea air conditioner, but also optimized energy consumption throughout the summer season.
Our expertise in Saint-Constant and throughout the South Shore
This intervention is just one example of the many HVAC service calls we carry out each week in Saint-Constant , Brossard , La Prairie and Sainte-Julie . Our local team is familiar with the specific features of South Shore homes—from modern single-family homes to newer condos with high ceilings —and tailors each repair to the specific layout of the space.
Trust AirGreen , your local HVAC partner, for:
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Midea wall-mounted air conditioner repair ,
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preventive maintenance of all types of HVAC systems,
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and complete replacement with high energy efficiency models eligible for Quebec subsidies .