A sudden breakdown in the middle of winter on the North Shore
At AirGreen , we were recently called out for a service call in Boisbriand , on Montreal's North Shore , after a customer noticed that their Fujitsu wall-mounted heat pump was no longer producing hot air. The unit, located in the main entrance of the house, was displaying a red warning light and refused to start despite several restart attempts.
This situation is typical of safety shutdowns caused by internal sensor problems or dust buildup on the heat exchanger. In this case, the front panel had been removed by the owner before our arrival, revealing a clogged evaporator and a semi-seized fan motor .
Complete diagnosis by our HVAC technicians
Our technicians first checked the power supply: the circuit breaker and communication with the outdoor unit were functional. Then, we performed a voltage test on the indoor electronic board — a voltage imbalance was detected, indicating a damaged control board .
Further inspection confirmed that:
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The indoor fan motor was receiving power, but would not start;
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The evaporator was covered with a thin layer of frost , which prevented the temperature sensor from working properly;
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The electronic board showed signs of oxidation near the fan connectors.
Repair and replacement of parts
The intervention consisted of:
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Replace the Fujitsu internal electronic board with an original part supplied by our AirGreen warehouse;
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Clean and defrost the heat exchanger using a biodegradable cleaner;
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Lubricate and test the fan motor to confirm that it was not mechanically damaged;
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Reset the temperature sensors and reprogram the communication between the indoor and outdoor units.
After the replacement, we carried out a series of comprehensive tests:
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Automatic start without error;
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Stable heating cycle with hot air at 42°C at the outlet ;
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No abnormal noise detected;
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Power consumption within normal parameters.
Result: restored comfort and optimized performance
The Boisbriand customer found a perfectly functional, quiet and efficient system. Hot air was circulating throughout the house again after only 90 minutes of work .
Our technicians also took the time to explain the importance of regularly cleaning the turbine and filter—a simple but crucial step to prevent overheating and premature failure of the electronic boards.
What this case demonstrates
Fujitsu wall-mounted heat pumps are renowned for their reliability, but like any HVAC system, they require annual maintenance. A simple lack of maintenance or excessive condensation can lead to:
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Corrosion of electronic components ;
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Communication errors between units;
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A loss of energy efficiency of up to 30%.
By entrusting maintenance and repair to AirGreen, owners benefit from an accurate diagnosis, rapid service , and guaranteed original parts .
AirGreen: your HVAC partner in Montreal and on the North Shore
Whether in Montreal, Laval, Boisbriand, Terrebonne or Saint-Eustache , our teams intervene quickly to repair, maintain and optimize your Fujitsu, Gree, Midea and other recognized brand wall-mounted heat pumps .
Each service call is handled with rigor, transparency and a clear objective: to restore your comfort as quickly as possible .