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Réparation d’une thermopompe murale Fujitsu à Saint-Laurent
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Repair of a Fujitsu wall-mounted heat pump in Saint-Laurent

An urgent service call for a broken Fujitsu wall-mounted heat pump in Saint-Laurent

At AirGreen , our technicians work daily in homes in Saint-Laurent , Montreal, to diagnose and repair wall-mounted HVAC systems of all brands. Recently, a customer contacted us because their Fujitsu wall-mounted heat pump was no longer producing cold air, despite a light display indicating that the unit was operating normally.

The failure occurred after a few weeks of continuous use in spring, a period when temperature fluctuations often put electronic components under strain.

Fujitsu System Description

The unit in question was a Fujitsu Halcyon wall-mounted heat pump , operating on R-410A refrigerant . This compact model, installed above an interior door, provided both heating and cooling for a medium-sized condo unit. The installation, typical of buildings in the Saint-Laurent sector, relied on an outdoor condenser mounted on a wall bracket, connected to the indoor unit by insulated refrigerant lines.

These Fujitsu models are known for their reliability, but like any HVAC system, they require regular maintenance to maintain their efficiency and prevent sensor or electronic board failures.

Fault diagnosis

Upon our arrival, our technician began with a complete diagnosis of the indoor unit :

  • Checking the indicator lights and the built-in error code;

  • Measurement of the air temperature at the unit outlet (almost identical to that of the room);

  • Blower fan inspection;

  • Checking the ambient temperature sensor and the main control board .

The flashing error code indicated a communication problem between the indoor unit and the outdoor condenser . This fault, which is quite common on Halcyon models, can be caused by:

  1. An oxidized or damaged communication cable;

  2. A faulty electronic card;

  3. A weakened start capacitor preventing the compressor from responding properly.

Intervention and repair

After safely disconnecting the system, our team proceeded with the following steps:

  1. Checked the electrical continuity of the cable connecting the two units – one of the wires showed abnormal resistance due to internal oxidation.

  2. Cleaning and replacement of the defective section using shielded wire conforming to Fujitsu specifications.

  3. Inspection of the indoor unit control module : the fan control relay showed signs of overheating.

  4. Relay replacement and electronic board recalibration using our diagnostic reader.

  5. System reboot and complete cold/hot cycle test .

The compressor restarted normally, and a differential of 10.3°C was observed between the intake air and the blown air, confirming the return to optimal performance.

Result and advice to the client

After the repair, the Fujitsu wall-mounted heat pump returned to its quiet and stable operation. The customer immediately felt the difference: thermal comfort restored without temperature fluctuations or frequent restarts.

Our recommendations focused on:

  • Annual maintenance including cleaning of the internal filter and the external coil;

  • A preventive check of communication cables before each heating season;

  • Protection of the electronic board against overvoltages using a suitable regulator.

AirGreen expertise in Saint-Laurent and across Greater Montreal

At AirGreen, we combine technical experience and a human approach to offer fast and lasting HVAC repairs in Montreal, Laval, on the North Shore and the South Shore .
Our technicians are trained on major brands of wall-mounted heat pumps, including Fujitsu, Gree, Midea, Sharp, Hitachi, Goodman and Bosch .

Each AirGreen intervention is distinguished by:

  • Accurate diagnosis , supported by electronic calibration tools;

  • Exclusive use of original parts ;

  • A proactive and educational approach to the client.

We know that a well-functioning HVAC system is essential to the comfort of a Montreal home, and our mission is to ensure that every appliance we repair returns to its original performance, while extending its lifespan.

In summary

  • Brand: Fujitsu

  • Type: Halcyon R-410A wall-mounted heat pump

  • Problem: Communication interrupted between units, faulty relay

  • Solution: Cable repair, relay replacement, board recalibration

  • Result: Performance restored, comfort restored

  • Location: Saint-Laurent, Montreal

At AirGreen, every repair is an opportunity to demonstrate our rigor and commitment to quality. Whether it's a simple inspection or a complex breakdown, we provide fast, reliable, and professional service throughout Greater Montreal.