A quick service call for comfort restored in Saint-Laurent
At AirGreen , our team of specialized HVAC repair technicians operates daily throughout the Greater Montreal area to diagnose and restart wall-mounted air conditioning equipment. On this day, we were called to a charming duplex in the Saint-Laurent district to troubleshoot a Mitsubishi Electric wall-mounted air conditioner , a popular model known for its reliability but which, like any appliance, sometimes requires expert attention.
Symptoms observed: a device that blows warm air
The customer contacted us after noticing that their Mitsubishi wall-mounted air conditioner was no longer cooling properly. Even when the remote control was set to 18°C, the indoor unit blew lukewarm air , unable to lower the room temperature. No error lights were displayed, but the compressor sound seemed erratic—a typical sign of a lack of refrigerant or a problem with the temperature sensor .
Complete diagnosis by our certified HVAC technicians
Upon our arrival, we carried out a series of methodical checks:
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Visual inspection and filter cleaning : The filters were slightly clogged with dust, reducing airflow.
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Checked the fan and coil : no trace of frost, but a slight oily deposit on the connections suggested a micro-leak of refrigerant .
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Refrigeration circuit pressure test : confirmed! The pressure level was below the standard for this model.
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Checked wiring and internal sensors : no electrical faults detected.
The final diagnosis: minor leak of R410A refrigerant at the flare connection of the suction line.
Intervention: repair of the leak and complete recharge of the system
Our technicians undertook the repair in several stages:
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Tightening and re-bracing of flare fittings ;
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Nitrogen cleaning of the circuit to remove moisture;
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Pressure gauge leak test for 30 minutes to ensure no leaks;
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Complete recharge of the refrigeration circuit according to the specifications of the Mitsubishi manufacturer;
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Final performance test : After 15 minutes of operation, the blowing temperature dropped from 26°C to 10°C — proof that the heat pump was operating at full capacity again.
Result: restored comfort and optimal efficiency
Once the work was completed, the customer immediately noticed the difference. The wall-mounted unit was once again blowing cool, steady air , with the quiet flow typical of Mitsubishi systems. We also explained to the customer the importance of annual maintenance : cleaning the filters, inspecting the fittings, and checking the pressure to prevent future leaks.
AirGreen Tips to Extend the Life of Your Wall-Mounted Air Conditioner
Our experts recommend:
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Clean the filters every two months during the summer season;
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Avoid operating the appliance at maximum temperature continuously , which strains the compressor;
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Have the refrigerant level checked every two years;
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Schedule preventative maintenance in the spring before the heatwave.
Why choose AirGreen for your HVAC repairs in Montreal and Laval?
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Certified and trained technicians on all major brands (Mitsubishi, Fujitsu, Gree, Midea, LG, Daikin, etc.);
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Fast and transparent service , no hidden costs;
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Warranty on repairs and replaced parts ;
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Presence throughout the Greater Montreal region : Montreal, Laval, Longueuil, North Shore and South Shore.
At AirGreen , we make it our mission to restore your home's comfort quickly and sustainably —with the same care we would if it were our own.
Conclusion: A refurbished Mitsubishi wall-mounted air conditioner in Saint-Laurent
Thanks to a fast, methodical and certified intervention , we allowed this customer to regain optimal comfort the same day . This type of repair, although common, underlines the importance of regular maintenance and the expertise of a certified professional to ensure the longevity and performance of a wall-mounted HVAC system.