A call for an aging wall system
In a quiet residence in Sainte-Thérèse , on Montreal's North Shore , our AirGreen team was called in to repair a Mitsubishi wall-mounted air conditioner that was no longer producing cold air. The client, who had owned the house for over ten years, mentioned that the system—a beige wall-mounted model from the brand's first generations—had always worked well until early summer, when the blown air remained lukewarm, even in maximum cooling mode.
Upon our arrival, we identified an old Mitsubishi Electric model MS-A09WA , a device known for its durability, but whose several electronic and mechanical components show signs of aging after a decade of intensive service.
Diagnosis: a combined fault between the capacitor and the compressor
Our technicians undertook a complete diagnosis using the AirGreen procedure:
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Electrical check – no abnormalities on the circuit breaker side or voltage to the outdoor unit.
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Testing the communication signal between the indoor and outdoor units: signal present but weak.
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Compressor current measurement : very low, indicating an inability to start.
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Start capacitor inspection : measured value at 6 µF instead of the required 12 µF.
Because the capacitor was under-capacity, the compressor was not receiving the initial boost needed to start. However, a second thermal test revealed excessive compressor winding temperature, suggesting internal wear of the motor after years of operation.
Intervention: replacement of the capacitor and complete test of the compressor
At AirGreen, we always take a methodical approach before recommending a complete replacement. Therefore, we have:
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Replaced the starting capacitor with a genuine Mitsubishi part, suitable for the MS-A09WA model.
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Cleaned the fins of the outdoor condenser, clogged with accumulated dust and pollen.
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Checked the R-22 refrigerant charge (still used on this model, but now discontinued).
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Performed a restart under supervision using an ammeter to monitor current stability.
Result: The compressor restarted, but with a slight rubbing noise – a sign of advanced mechanical wear. After 20 minutes of operation, the air was coming out at 12°C , a sign that the system was cooling effectively again.
AirGreen Tips and Recommendations
We advised the customer to plan for a system replacement within the next 12 to 18 months , before the compressor's end of life. We presented modern options using the more environmentally friendly and efficient R-32 refrigerant , including the Midea Premier 12,000 BTU range and the Fujitsu Halcyon XLTH series , which are perfectly suited to Quebec's climate conditions.
In the meantime, we have:
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checked the proper evacuation of condensates ;
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replaced the dirty air filter ;
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applied a mild antibacterial treatment to the coils.
These measures ensure reliable operation for the summer season while optimizing the energy efficiency of the existing system.
Expertise and rigor: the AirGreen brand
This type of intervention perfectly reflects our approach at AirGreen: combining in-depth technical diagnostics with honest advice based on the client's economic and energy reality. Repairing when viable, but always with a long-term vision.
We work daily on Mitsubishi, Fujitsu, Sharp, Gree, Midea and Zephyr wall-mounted air conditioners throughout Montreal, Laval, Longueuil, the North Shore and the South Shore , guaranteeing:
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an accurate diagnosis ,
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original parts ,
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fast and transparent service ,
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and above all, lasting comfort for our residential and commercial customers.
Conclusion: a summer saved, a plan for the future drawn up
Thanks to this targeted repair of the Mitsubishi wall-mounted air conditioner in Sainte-Thérèse , the customer was able to regain his comfort in less than 24 hours. Our personalized follow-up will allow him, when the time comes, to migrate to a modern, high-energy efficiency solution, while taking advantage of provincial subsidies for the conversion to a system using R-32 .
Once again, AirGreen 's efficiency and rigor made the difference — a service that is technical, human and sustainable, reflecting our commitment to the HVAC field in Montreal and its surrounding areas .