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Réparation d’une thermopompe MultiZone Fujitsu à Boucherville
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Fujitsu MultiZone Heat Pump Repair in Boucherville

Intervention on a MultiZone heating and air conditioning system with a breakdown

At AirGreen , we were called for an urgent service call in Boucherville , on the South Shore of Montreal , to work on a Fujitsu MultiZone heat pump installed in a single-family residence.
The customer noticed that none of the indoor units were blowing hot or cold air , although the lights on the remote control were lighting up normally. This type of symptom often indicates a problem with the outdoor unit , the central point of the MultiZone system.

Initial inspection: outdoor unit clogged and component faulty

Upon our arrival, our technician performed a complete inspection of the Fujitsu outdoor unit , which was mounted on a sturdy wall bracket, but partially clogged with dust and residue.
We quickly noticed:

  • Traces of oxidation on the top panel of the condenser;

  • A buildup of debris in the coil, reducing heat exchange;

  • A fluctuating power supply , indicated by an intermittent beep from the main module.

Using a digital multimeter and an electronic pressure gauge, we carried out a thorough diagnosis.

Diagnosis confirmed: damaged main control board

After verification:

  • The refrigerant circuit pressures were stable , excluding a refrigerant leak;

  • The compressor would not start, despite a valid signal from the thermostat;

  • The starter relay on the control board was no longer responding, confirming an electronic fault .

This type of failure is common on Fujitsu MultiZone systems exposed to humidity and voltage fluctuations—especially when the unit is installed near a gas line, as was the case here, increasing the risk of condensation around electrical connections.

Steps of repair

Our intervention took place in several precise stages:

  1. Complete power cut and site security.

  2. Removing the side panel to access the control board.

  3. Visual and electronic inspection of the board: charred areas near the main relay.

  4. Complete replacement of the original Fujitsu electronic card , calibrated and programmed according to the system serial number.

  5. Thorough cleaning of the coil and fan with compressed air and biodegradable cleaner.

  6. Reassembly and re-energization followed by complete tests on each interior zone.

Once the repair was completed, the four wall units connected to this MultiZone resumed normal operation, with constant airflow and perfectly stable temperatures in each room.

Performance Verification

Using an infrared thermometer and a digital pressure gauge, we confirmed:

  • A temperature delta of 12°C between the inlet air and the blown air;

  • Suction pressure in accordance with Fujitsu values;

  • Optimized power consumption , without overcurrent on start-up.

We have also updated the card's internal firmware to ensure optimal compatibility with the new MultiZone communication module.

Result: comfort restored and system made more reliable

Within two hours, the Fujitsu HVAC system was fully operational again.
The client found comfort throughout the house—efficient heating in the living room, air conditioning in the bedrooms, and a noticeable reduction in outside noise.

We recommended to him:

  • To have the outdoor coil cleaned every spring ;

  • Install a surge protector to protect electronics from voltage fluctuations;

  • And schedule an annual AirGreen inspection , ensuring the longevity of the MultiZone system.

AirGreen expertise: precision and durability serving comfort

Fujitsu MultiZone systems are renowned for their performance and flexibility, but their electronic complexity requires certified expertise .
At AirGreen, our technicians have the tools and skills necessary to quickly intervene on this equipment, whether it is:

  • Electronic failures (cards, relays, sensors);

  • Communication problems between units ;

  • Pressure and zone balancing settings .

Our coverage extends to Montreal, Laval, Longueuil, the North Shore and the South Shore , guaranteeing fast, professional and sustainable local service.

Another successful case from AirGreen

This Fujitsu MultiZone heat pump repair in Boucherville perfectly illustrates our commitment to providing precise and long-lasting technical service .
Thanks to expert intervention , a complex breakdown was resolved in a single trip, restoring the customer to the comfort and performance he expected from his high-end HVAC system.