A service call for a Fujitsu heat pump that no longer heats
At AirGreen , we are regularly called upon to address issues with insufficient heating on Fujitsu wall-mounted heat pumps . On that day, our team visited a brick duplex in the Rosemont–La Petite-Patrie neighborhood of Montreal , where the customer reported that their heat pump was no longer producing heat, despite outside temperatures approaching zero.
Initial diagnosis: compressor stopped
The outdoor unit, a Fujitsu Halcyon model, was installed on a well-ventilated rear balcony. Upon arrival, we noticed that the compressor would not start , although the fan was operating normally. This behavior is often related to a communication problem between the indoor and outdoor electronic boards, or a faulty temperature sensor .
To confirm the diagnosis, our technicians began by:
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Check the supply voltage at the main terminal.
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Inspect the communication link (14/4 cable between units).
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Read the error codes displayed on the indoor unit.
The error code detected corresponded to an outdoor air sensor (thermistor) anomaly , preventing the compressor from starting in heating mode.
Step 1: Replacing the outdoor temperature sensor
We disconnected the main power supply, removed the side panel, and located the faulty thermistor. It showed inconsistent resistance at room temperature, confirming its failure.
A genuine Fujitsu part was installed, calibrated according to the manufacturer's specifications. This sensor is essential to allow the electronic board to regulate the compressor's operation according to the outside temperature—a critical element for Quebec winters .
Step 2: Complete preventive inspection
Before putting the device back into service, we took advantage of the intervention to carry out complete preventive maintenance :
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Cleaning the condenser coil , slightly clogged with dust and pollen.
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Checking the R-410A refrigerant level using electronic pressure gauges.
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Inspection of electrical connections and relays on the main board.
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Automatic defrost test , to ensure that the system operates correctly during low temperatures.
Step 3: Test and validate the repair
After reassembly and power up, the compressor restarted normally . The heat pump quickly reached its set temperature, providing warm and stable air inside. We monitored the complete cycle for about fifteen minutes to confirm the stability of the pressures and the blowing temperature.
Result: restored performance and satisfied customer
The system was fully operational again, with no abnormal noise or temperature fluctuations. The customer noted an immediate reduction in electricity consumption , as the heat pump was now operating without the need for additional heating.
We also advised the client to:
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Clean the interior filters every month during the heating season.
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Schedule annual maintenance to prevent sensor failures.
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Install a protective roof over the outdoor unit to limit the accumulation of snow and ice.
Why entrust your Fujitsu heat pump repair to AirGreen?
Fujitsu Halcyon heat pumps are known for their reliability, but like any HVAC system, they require maintenance and accurate diagnosis in the event of a breakdown. At AirGreen , our technicians:
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Are trained and certified Fujitsu ,
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Use original parts ,
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And operate throughout Greater Montreal , including Rosemont, Outremont, Plateau-Mont-Royal, Laval and Longueuil .
We guarantee professional, fast and transparent service - each customer receives a detailed diagnostic report and personalized recommendations to extend the life of their equipment.
AirGreen: Local HVAC Expertise You Can Count On
With Quebec's harsh winters, a reliable heat pump is essential. Our mission at AirGreen is to ensure that every HVAC system is operating optimally, whether it's maintenance , repair , or a complete installation .
Thanks to our specialized interventions, our clients benefit from lasting comfort and better energy efficiency , while reducing their long-term costs.