Roof intervention for a broken Hexzair system
At AirGreen , we were recently called upon for an HVAC service call in a commercial building in Brossard , on the South Shore of Montreal. The intervention concerned a Hexzair brand wall-mounted heat pump , installed on the roof, which was no longer responding to the commands of the interior system. This type of configuration, typical of multi-unit buildings, requires special know-how due to direct exposure to the elements and the extended routing of the refrigeration lines.
Symptoms observed before our arrival
The client contacted us after noticing several worrying signs:
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The indoor module was no longer blowing cold air despite an active air conditioning request;
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The outdoor unit would no longer start ;
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A flashing red light appeared on the indoor module, indicating a communication or voltage anomaly.
These symptoms suggested an electrical or electronic problem with the compressor or control circuit.
Complete on-site diagnosis
Upon our arrival, our certified technicians performed a detailed analysis of the Hexzair heat pump, a 12,000 BTU single-zone wall-mounted model typically used for offices and small businesses.
The diagnostic steps included:
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Power supply check : We confirmed the presence of a stable voltage of 240V at the terminal block of the outdoor unit.
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Inspection of the control wiring between the indoor and outdoor units. Slight oxidation was visible on the connectors due to humidity.
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Compressor and fan test : The fan motor operated normally, but the compressor remained inactive.
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Reading the error code via the Hexzair control panel: the code “E6” indicated a loss of communication between the modules .
Action: Restore communication and replace the control board
After isolating the source of the problem, we undertook a complete repair :
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Cleaning and deoxidizing connectors using a professional dielectric cleaner;
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Testing the communication signal with a digital multimeter;
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Replacement of the outdoor unit main control board (PCB) , damaged by a previous power surge;
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Complete reset of the Hexzair system to restore module synchronization.
Once these steps were completed, the heat pump restarted normally. The compressor started, and the refrigeration cycle stabilized at pressures consistent with the manufacturer's standards.
Result: restored comfort and optimized performance
After the repair, we performed several measurements to verify performance:
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Blown air temperature : 11°C in air conditioning mode;
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R-410A refrigerant pressure : stable at 125 psi low pressure / 390 psi high pressure;
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Compressor electrical current : within the model's nominal limits.
The Hexzair heat pump has thus regained its initial energy efficiency , ensuring constant comfort inside the premises. We have also secured the cables and repositioned the conduits to prevent any water infiltration during rain.
Prevention: the importance of annual roof maintenance
Outdoor units installed on a flat roof are particularly exposed:
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Extreme temperature variations (from -30°C to +35°C);
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Accumulation of dust and debris ;
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Increased risk of moisture in electrical connections .
We recommended that the customer perform biannual preventive maintenance , including cleaning the condenser, checking the refrigerant pressure, and calibrating the temperature sensor. These measures help prevent electronic failures , which are common in high-rise units.
AirGreen: your HVAC partner in Brossard and throughout Greater Montreal
At AirGreen , we offer you our complete expertise in the repair, maintenance, and installation of residential and commercial HVAC systems . We work on all brands— Hexzair, Midea, Fujitsu, Gree, Mitsubishi, Zephyr, Lennox , and many others—in Montreal, Laval, the North Shore, and the South Shore .
Each intervention is carried out with rigor, transparency, and attention to detail. We know that thermal comfort can't wait: our technicians are available quickly to restore your HVAC systems to perfect working order.
Conclusion: A successful repair on the Brossard roof
This intervention on a Hexzair heat pump in Brossard demonstrates our ability to efficiently diagnose and resolve complex faults, even in technical environments such as commercial rooftops. Thanks to our expertise, the client received a reliable, efficient, and durable system—ready to withstand Quebec's temperature fluctuations.
AirGreen – Experts in heat pumps and HVAC systems in Montreal, Laval, North Shore and South Shore.
Responsiveness, precision and professionalism with every service call.