A roof service call reveals a critical electrical fault
At AirGreen , our HVAC repair services often go beyond simply restarting a unit: they ensure the safety, performance, and longevity of your installations. Recently, our team was called to Sainte-Thérèse , on Montreal's North Shore , to inspect a Lennox central heat pump that had stopped working after several days of intense heat.
The system was installed on the roof of a commercial building. The outdoor units, while robust, were subjected to heavy exposure to the sun and harsh weather. Our client reported frequent shutdowns , followed by power trips at the main panel—a clear sign of a power problem or compressor overload.
Diagnosis: water infiltration and corroded electrical connectors
Upon our arrival, we carried out a complete diagnosis:
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Checking the voltages on the circuit breakers and connection boxes (visible in the photo).
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Visual inspection of the electrical connections, where we noticed significant oxidation around the grommets and junction boxes.
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Continuity test to confirm that no cables were cut or charred.
The verdict: Moisture had seeped into the connectors , causing internal corrosion and an intermittent short circuit on the power line of one of the units. This type of failure is common on exposed roofs, where heat and rain cycles accelerate the degradation of seals and cable glands.
Intervention: replacement and securing of electrical boxes
Our technicians carried out a multi-stage intervention:
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Cut off the general power supply to secure the work area.
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Complete removal of defective housings , whose seals showed signs of rust.
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Cleaning the cables with a deoxidizing solution and protection with heat-shrink tubing .
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Replacement of electrical boxes with new models with IP65 protection rating , better suited to outdoor conditions.
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Renovation of wall seals around cable entries to ensure perfect watertightness .
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Complete start-up test , including verification of inrush current and operating voltage.
Thanks to these interventions, the Lennox heat pump regained stable and secure power . The compressor restarted without incident, and the system resumed normal operation, with excellent energy efficiency.
Result: restored safety and sustainable performance
After replacing the electrical components and checking the refrigeration cycle, the system returned to its nominal performance. The customer immediately noticed:
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Increased temperature stability inside.
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A reduction in operating noise .
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A complete elimination of disjunctions .
Our technicians also recommended an annual inspection of electrical boxes to prevent future leaks, particularly on rooftop installations. This simple measure can prevent costly repairs and ensure continued comfort year-round.
AirGreen expertise in Sainte-Thérèse and on the North Shore
This type of intervention demonstrates the importance of rigorous maintenance of HVAC systems installed in exposed environments. At AirGreen, we put our know-how at the service of residences, businesses and condominiums in Montreal, Laval, Longueuil, the North Shore and the South Shore , to ensure the reliability and safety of Lennox, Midea, Fujitsu, Trane, Goodman systems , and several other trusted brands.
Whether it's for a central heat pump repair , a preventive inspection or an electrical fault diagnosis , our certified technicians provide professional, fast service that meets the highest industry standards.
At AirGreen, your comfort and safety always come first.