A roof intervention in the middle of Montreal summer
At AirGreen , we regularly receive service calls for HVAC systems installed on the flat roofs of residential and commercial buildings. On this day, our team went to the Côte-des-Neiges–Notre-Dame-de-Grâce neighborhood of Montreal to diagnose a Zephyr wall-mounted heat pump that had stopped working after several weeks of intense heat.
The outdoor unit, installed on treated wood supports to insulate it from the roof gravel, appeared intact at first glance. However, the customer noticed that the heat pump was no longer producing cooling and that a slight clicking noise was heard each time it tried to start it.
Diagnosis: a compressor blocked by a faulty capacitor
After a complete inspection of the Zephyr unit, our technicians carried out several checks:
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Power supply : Correct voltage at the input terminal.
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Communication between indoor and outdoor units : stable, no damaged wires.
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Compressor start capacitor : tested with multimeter, showing capacitance value below manufacturer's tolerance .
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Compressor : Temporarily blocked due to faulty capacitor, preventing the refrigeration cycle from starting.
This type of problem is common on roofs exposed to direct sunlight. Capacitors, which are sensitive to heat, gradually lose their capacity after several years of exposure, especially during summer heat waves.
Repair: capacitor replacement and complete recommissioning
Our technicians replaced the original Zephyr starter capacitor with a compatible part of equivalent quality. The operation required:
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A complete system shutdown .
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Partial disassembly of the condenser side panel .
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Replacement and connection of the new capacitor according to the manufacturer's specifications.
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A load start test to validate the pressure of the refrigeration circuit.
As soon as the power was turned back on, the heat pump restarted without any problems. We checked the indoor blowing temperature (around 12°C in air conditioning mode), confirming a return to optimal performance .
Precautions and maintenance advice
In order to avoid the problem recurring, we recommended to the owner:
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Have the Zephyr heat pump inspected twice a year , especially before hot weather and before winter.
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Keep the roof area clear to ensure good air circulation around the condenser.
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Opt for a lightweight roof shade if possible, to reduce the ambient temperature around the unit on hotter days.
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To monitor for abnormal noises (clicking, vibrations) which may indicate a capacitor at the end of its life.
These simple actions extend the life of the appliance and reduce the risk of breakdown during periods of high energy demand.
AirGreen know-how: precision, safety and reliability
At AirGreen, every HVAC repair is carried out with attention to detail and safety in mind. Working on rooftop systems requires careful planning, including:
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Securing the work perimeter .
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Calibrated tools for electrical diagnostics .
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A post-intervention check ensuring that the fixings, conduits and wiring remain compliant with current standards.
This approach not only ensures a rapid return of interior comfort , but also increased longevity of the repaired Zephyr system.
Result: restored performance and satisfied customer
After the repair, the Zephyr heat pump resumed normal operation, once again providing stable and quiet cooling . The customer, satisfied with the transparent diagnosis and the speed of the intervention, chose to subscribe to our AirGreen preventive maintenance program , an ideal solution to avoid seasonal surprises.
Thanks to our expertise in heat pump repair in Montreal , we assure each customer—whether they live on the North Shore, South Shore, Laval , or in a central neighborhood like NDG —fast, professional, and long-lasting service.
In summary:
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Problem detected: Defective starting capacitor.
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Solution: replace the part and check the refrigeration circuit.
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Result: Zephyr heat pump fully operational again.
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Location: Côte-des-Neiges–Notre-Dame-de-Grâce, Montreal.
AirGreen , your trusted HVAC partner for all Zephyr , Midea , Fujitsu , Gree , Lennox heat pump repairs and more, throughout Greater Montreal.