A breakdown in the middle of winter: rapid intervention on the North Shore
On this freezing morning in Blainville , one of our customers contacted us after noticing that his Mitsubishi Electric wall-mounted heat pump was no longer blowing hot air. The outdoor unit, partially buried in snow, was exhibiting abnormal behavior: irregular noise , no automatic defrost, and a flashing light on the indoor unit.
At AirGreen , we know that outdoor HVAC systems on the North Shore are subject to particularly demanding conditions. Intense cold, ice, and thaw cycles can put a strain on the mechanical and electronic components of heat pumps. Our team dispatched an emergency technician to diagnose the problem on-site.
Detailed on-site diagnosis
Once on site, our technician immediately observed:
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Significant ice buildup on the bottom of the condenser, preventing normal ventilation of the unit.
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Heat exchange fins clogged with debris and blown snow.
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Twisted wall bracket , causing the compressor to tilt slightly.
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Flashing error light indicating a code related to the outdoor temperature sensor.
After performing the voltage tests and measuring the pressure of the R-410A refrigerant, we confirmed two issues:
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Faulty outside temperature sensor , distorting the defrost cycle.
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Overworked compressor , due to restricted airflow and gradual overheating.
Complete repair and upgrade
The repair took place in several carefully planned stages:
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Complete removal of the Mitsubishi outdoor unit for workshop defrosting and structural inspection.
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Replacement of the temperature sensor with an original Mitsubishi Electric part.
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Deep cleaning of the coils and partial straightening of the wall support.
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Reinstallation with precise recalibration of the unit to ensure optimal condensate flow.
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Complete system test : pressures, compressor intensity, and verification of automatic defrost mode.
Once the repair was completed, the wall-mounted heat pump resumed normal operation. The hot air flow was stable , and the defrost sequence was triggered at the correct frequency.
Result: efficiency restored despite the cold
The client, who was entirely dependent on his heat pump for primary heating , was able to regain immediate comfort in his home. Our final measurements showed:
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A coefficient of performance (COP) that meets Mitsubishi standards for temperatures down to -15°C.
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Automatic defrosting that works smoothly and regularly.
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Optimized energy consumption , thanks to a calibrated probe and stable refrigerant pressure.
We also advised the client to install an approved protective shelter to reduce direct exposure to precipitation and to schedule annual preventative maintenance in the spring.
AirGreen expertise serving the North Shore
The extreme winter conditions on the North Shore—particularly in Blainville, Sainte-Thérèse, and Bois-des-Filions —require rigorous maintenance of wall-mounted heat pumps. At AirGreen , we adapt our interventions to these realities:
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Fast on-site repairs even in winter.
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Accurate electronic diagnostics on recent Mitsubishi, Fujitsu, Gree and Sharp models.
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Replacement of sensors, electronic cards and fans with original parts.
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Personalized advice to protect installations against ice and salt.
Our goal: to provide lasting repairs and maintain consistent comfort throughout the year.
Why trust AirGreen for your Mitsubishi repairs?
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Mitsubishi Electric certified technicians .
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Quick availability throughout Greater Montreal: Montreal, Laval, Longueuil, North Shore and South Shore.
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Guaranteed original parts to extend the life of your device.
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Professional and transparent customer service , with no surprises on billing.
At AirGreen, we combine technical rigor and human proximity to guarantee each customer a reliable intervention, whatever the weather.