A freezing day, a snowy roof, and an HVAC emergency
In the middle of winter, a building owner in Lachine contacted us about a complete heating failure on his Kanion central HVAC system. The outdoor unit, installed on the building's roof, was partially buried under snow, making the situation even more critical. In this type of context, rapid intervention and thorough diagnosis are essential: in winter, every hour without heating can pose risks to the plumbing, the building, and the comfort of the occupants.
At AirGreen , we understand that good HVAC service relies as much on technical expertise as it does on preparation. Despite the extreme weather conditions, our team responded the same day with the necessary equipment to work efficiently in a snowy and windy environment.
Diagnosis: an electrical fault masked by the cold
Upon arrival, we observed two units on the roof: a recent Kanion central heat pump , and an older, non-functional condenser still connected to the power supply. According to the customer, the system had stopped heating the day before after an interrupted defrost cycle.
Our technicians proceeded in stages:
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Power Check : The Kanion main unit was no longer receiving the expected power.
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Fuse and circuit breaker inspection : No fuses were blown, but the control box showed signs of oxidation caused by frozen condensation.
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Analysis of the compressor and refrigerant gas pressures : the R-410A charge was adequate, which ruled out a leak.
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Defrost module check : the outside temperature sensor was no longer responding, preventing the electronic card from restarting the normal heating cycle.
The diagnosis was clear: a combined failure of the sensor and the control relay was preventing the heat pump from correctly performing its defrost sequence.
Technical intervention: precision and efficiency in extreme cold
Once the problem was identified, our technician carefully undertook the repair, despite the temperature being around -18°C and a strong roof wind.
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Replaced the temperature sensor with a Kanion compatible model, thermally insulated to prevent reading errors due to frost.
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Complete cleaning of the control box : removal of moisture and application of a dielectric sealant to prevent future corrosion.
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Checked the electrical wiring between the two units: several connectors showed traces of frost, corrected using an insulating treatment.
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Complete defrost cycle test : After powering up, the system restarted normally, with stable warm airflow after a few minutes.
To finalize, we checked the discharge temperature in the interior main duct and confirmed a return to full heating capacity .
Prevention and recommendations for roof installations
Rooftop heat pump installations, common in Lachine and several Montreal neighborhoods, require special attention during the winter. Our recommendations to the client included:
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Regularly clear snow around the unit to prevent fan obstruction.
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Install a wind barrier if the unit is exposed to direct gusts.
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Inspect the control box before each winter to prevent water infiltration and freezing.
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Schedule preventative maintenance in the spring , before the air conditioning season.
These simple actions help reduce the risk of breakdown and extend the life of the Kanion system, while ensuring optimal comfort all year round.
AirGreen expertise in the field
Our intervention in Lachine perfectly illustrates the versatility of our AirGreen team , capable of working in extreme conditions while maintaining a high level of precision. Thanks to our experience on commercial and residential roofs, we are used to managing complex repairs on central systems in winter, whether they are from Kanion, Lennox, Goodman, Trane, Bosch, or Midea .
Each call is an opportunity for us to demonstrate our expertise: a combination of technical rigor, detailed analysis and compliance with safety standards.
Result: comfort restored and customer satisfied
After the final tests, the customer immediately noticed the difference: a stable indoor temperature, quiet operation, and regular defrosting . We left the system under observation for a few additional minutes to confirm that the heat pump was returning to its normal cycles.
This Kanion central heat pump repair in Lachine not only restored heat, but also prevented potential future breakdowns thanks to the fixes applied and maintenance recommendations.