An indoor unit breaks down at the start of the warm season
At AirGreen , we recently received a service call in Saint-Lambert for a Fujitsu wall-mounted air conditioner repair . The customer, a resident of a modern condominium, had noticed that his unit was no longer producing cold air despite the usual fan noise. With the arrival of the first warm days of May, he wanted to quickly regain comfort in his living space.
Upon our arrival, the Fujitsu indoor unit—typical of a compact wall-mounted model from the Halcyon range —had already been opened by the customer, revealing an exposed evaporator and a partially disconnected control panel . An ideal situation to begin a detailed diagnosis.
Diagnosis: Communication failure between units
Our technicians first checked the status of the connections between the indoor unit and the outdoor compressor. The control module indicator light was flashing with a Fujitsu-specific error code , indicating a communication failure between the two modules .
When measuring the voltage on terminals 2 and 3 of the main connector, we noticed an irregular fluctuation, indicating a damaged control wire or a loose connection. After careful inspection, the cause was quickly identified: a severed signal cable near the wall pass-through, probably caused by overtightening during a previous installation.
Repair and recommissioning
We replaced the defective cable section and reconnected it with high-temperature insulating terminal blocks , in accordance with Fujitsu standards.
Next, we tested the indoor unit's electronic board. No faults were detected, and communication was restored upon reboot. The diagnostic screen now displayed the code “00”—indicating normal operation.
Once the system is restarted:
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the wall unit fan has resumed its nominal speed,
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the outdoor compressor started after a 3-minute delay,
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and the air blown out of the coil showed a stable temperature of 9°C after only 7 minutes.
Complete cleaning and preventive maintenance
Taking advantage of the partial disassembly, we carried out a thorough cleaning of the evaporator and the helical fan . The evaporator, covered with a fine film of dust, risked reducing the system's efficiency and increasing power consumption.
Cleaning was carried out with a specialized biodegradable product for aluminum surfaces, followed by a low-pressure rinse to avoid damaging the fins. We also disinfected the condensate tray and checked that the drain was flowing properly—an often overlooked but essential point to avoid water leaks and unpleasant odors.
Results and recommendations
After these interventions, the Fujitsu wall-mounted air conditioner regained its full efficiency. The customer immediately noticed the difference: stronger blowing, cooler air and quieter operation .
Our technicians left him some recommendations to extend the life of his device:
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Clean filters every 4 to 6 weeks during the summer season.
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Avoid turning off the main power supply when the system is in standby mode, in order to preserve communication between the electronic boards.
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Schedule an annual inspection before May to anticipate any breakdowns before the heatwave.
AirGreen expertise in Saint-Lambert and throughout Greater Montreal
At AirGreen , we specialize in the repair and maintenance of Fujitsu HVAC systems , whether wall-mounted, multi-zone heat pumps or central air conditioners .
We respond quickly in Montreal, Laval, Longueuil, on the North Shore and the South Shore , with fully equipped intervention vehicles to diagnose and repair the majority of breakdowns on site.
Every service is performed by certified technicians who are familiar with the protocols of major manufacturers—Fujitsu, Gree, Sharp, Midea, Zephyr, LG, and many more.
If your Fujitsu air conditioner is showing signs of weakness—abnormal noise, lukewarm air, water leaks, or flashing lights— call AirGreen . We guarantee fast, professional, and long-lasting service, tailored to your comfort.