When additional heating becomes essential in the middle of spring
At AirGreen , we regularly receive service calls at the end of winter, when wall-mounted heat pumps show the first signs of fatigue after several months of continuous use. This was the case in Ville Mont-Royal , where a customer contacted us about a Fujitsu wall-mounted unit that was no longer blowing hot air, despite a correctly set thermostat.
Context and initial findings
The client, a typical single-family home owner in the area, was using this Fujitsu Halcyon Series wall-mounted heat pump as his primary source of supplemental heating for the living room. The unit, installed above an antique piece of furniture, appeared to be in good condition. However, upon arrival, we noticed a slight overheating odor and a complete lack of hot airflow .
The basic inspection revealed:
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A flashing red light on the indoor module;
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No compressor noise coming from the outdoor unit;
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An air outlet temperature below 16°C, even in heating mode.
These symptoms indicated a communication problem between the indoor and outdoor units , typical of older Fujitsu systems.
Detailed diagnosis: a faulty communication card
After removing the front cover, our technicians carried out a series of electrical checks:
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Supply voltage to the indoor unit: 240 V stable ;
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Control signal transmitted via the interconnected cable: no pulse detected ;
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Checking the power electronic board: abnormal resistance at the relay circuit .
The verdict was clear: the indoor unit's communication board was damaged. This failure prevented the control signal from reaching the outdoor unit, thus blocking the compressor from starting.
Intervention: replacement of the Fujitsu electronic card
At AirGreen, we have a stock of genuine Fujitsu parts to carry out this type of repair quickly. Our team has:
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Cut off the power supply to secure the intervention;
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Replaced the main control board with a compatible model of the same series;
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Checked the wiring between terminals L1-L2 and S1-S2 to ensure stable communication;
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Cleaned the temperature sensors and dusted the air filters;
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Tested full system reboot.
After the replacement, the Fujitsu heat pump restarted immediately . The outdoor compressor started, and we measured an airflow of 36°C at the outlet of the wall unit—a sign of efficient and stable heating.
Results and recommendations
The customer found immediate comfort , without excessive noise or abnormal odor. To prevent other similar breakdowns, we recommended:
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A complete annual maintenance including verification of electronic cards;
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Regular cleaning of internal filters (every 4 to 6 weeks);
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A visual inspection of the exterior wiring at each change of season;
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The installation of protection against electrical surges , often responsible for card failures on wall systems.
AirGreen: Fujitsu certified experts at your service
This intervention clearly illustrates the importance of accurate and rapid diagnosis. At AirGreen , our certified technicians are trained to repair Fujitsu, Gree, Midea, Daikin, and Sharp wall-mounted HVAC systems under all conditions—whether it's a communication failure, a refrigerant leak, or an inactive compressor.
We operate weekly in areas such as Ville Mont-Royal, Côte-des-Neiges, Outremont and Montréal-Nord , with specialized diagnostic tools and a stock of common parts to guarantee same-day restart.
A heat pump ready for summer
Before leaving the site, we checked the operation of the air conditioning mode , to assure the customer that their system would be ready for the warm season. The temperature and pressure readings were within Fujitsu specifications.
Result: a heat pump restored to 100% of its performance , quiet and efficient.
Thanks to a rapid and methodical intervention, AirGreen has once again demonstrated its expertise in repairing wall-mounted heat pumps in Montreal and Laval , bringing back to life a system essential for the comfort of occupants.