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Réparation d’une thermopompe murale Fujitsu à Rosemont–La Petite-Patrie (Montréal)
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Repair of a Fujitsu wall-mounted heat pump in Rosemont–La Petite-Patrie (Montreal)

Intervention on an electrical fault in the external terminal block

At AirGreen , we work daily in residential areas of Montreal for HVAC system repairs . This time, our team was dispatched to Rosemont–La Petite-Patrie to resolve an electrical outage affecting a Fujitsu wall-mounted heat pump installed on the flat roof of a typical apartment building in the area.

The context of the call

The customer, a triplex owner, contacted us after noticing that the outdoor unit of his Fujitsu heat pump was no longer starting , although the indoor unit was still displaying the commands correctly. There was no relay noise or compressor start-up. Another worrying clue: a faint burning smell coming from the outdoor electrical box.

On site, our technician accessed the outdoor unit installed on the flat roof covered with elastomeric membrane , a typical Montreal environment. Upon opening the electrical connection panel, he discovered oxidized and partially melted connections at the main power terminal block.

Accurate fault diagnosis

Our diagnostic steps were as follows:

  1. Initial visual inspection : immediate identification of blackened wiring near the terminal block and signs of overheating on the insulation.

  2. Continuity Check : Multimeter test revealed an open in the neutral line between the main power supply and the control board.

  3. Analysis of the electronic board : no apparent failure, but a carbon deposit indicated a risk of previous short circuit.

  4. Main circuit breaker check : the circuit breaker was intact, which confirmed that the fault was indeed coming from the connection between the wiring and the terminal block .

After these observations, we determined that the problem came from poor tightening of the power terminal block leading to progressive overheating, a frequent phenomenon in installations exposed to thermal variations in Montreal.

AirGreen intervention: safety restoration and sustainable repair

1. Replacement of damaged terminal block and cables

  • Complete disconnection of power supply.

  • Disassembly of the burnt terminal block and cleaning of carbon residue.

  • Installation of an original Fujitsu terminal block with stainless steel clamping screws .

  • Replaced the blackened cable segment with a tinned copper conductor of the appropriate gauge.

2. Cabling protection and routing review

  • Added an insulating grommet to protect cables from abrasion caused by vibrations.

  • Wrap the wiring with black heat shrink tubing , UV and moisture resistant.

  • Complete electrical continuity check after repair.

3. Complete system test

  • Reactivation of the current.

  • Observation of the gradual restart of the compressor and the external fan .

  • Terminal voltage control and inter-unit communication: all comply with Fujitsu specifications.

  • Measuring operating pressures: normal for an R410A system.

Result: a secure and efficient heat pump

After the repair, the Fujitsu wall-mounted heat pump restarted without any problems. We confirmed:

  • Indoor blowing temperature at 9°C in air conditioning mode.

  • No voltage fluctuation between the power terminals.

  • Stable communication between indoor and outdoor units.

The customer was able to regain comfort and peace of mind , knowing that their device was not only repaired, but also secured against any future risk of short circuit .

AirGreen Preventive Maintenance Tips

To avoid this type of problem, we recommend:

  • An annual inspection of the exterior electrical box, especially for units installed on flat roofs or in exposed environments.

  • Tighten electrical connections at least every two years.

  • A check of the insulating sheaths to prevent any moisture infiltration.

  • Scheduling a complete professional maintenance before each air conditioning season.

These simple actions extend the life of your HVAC system and reduce the risk of costly breakdowns.

AirGreen expertise in Montreal

At AirGreen , every service combines technical rigor, safety, and transparency . Our RBQ-certified, manufacturer-trained technicians work on all brands of wall-mounted heat pumps: Fujitsu, Gree, Midea, Sharp, Goodman, Bosch, Lennox, Trane, and many others .

We guarantee:

  • Compatible original parts .

  • A precise and documented diagnosis .

  • A durable repair that complies with current electrical standards.

Whether it's a minor breakdown or a complete restoration, our local teams cover all of Greater Montreal, Laval, Longueuil, the North Shore and the South Shore , with a rapid response time and constant attention to detail.

When to call AirGreen?

If your Fujitsu heat pump :

  • no longer starts,

  • trips the electrical panel,

  • or gives off a hot smell from the outdoor unit,
    It is crucial to intervene without delay.
    These symptoms often indicate deterioration of the terminal block or wiring , which can lead to complete failure or a risk of short circuit.

Call AirGreen – Climatisation & Chauffage , your trusted partner for HVAC system repair and maintenance in Montreal and the surrounding area.