A service call in a century-old duplex in Plateau-Outremont
At AirGreen , our technicians are often called upon to work in older buildings in Montreal where HVAC (heating, ventilation, and air conditioning) systems must deal with atypical electrical and architectural installations. This service call in Outremont perfectly illustrated this type of challenge: a Fujitsu wall-mounted air conditioner whose interior panel had been removed by the owner after it suddenly stopped working.
The customer, who was in the middle of a renovation, had tried to figure out the problem himself before contacting us. The unit no longer responded to the remote control and did not produce any light signals, even after resetting.
First step: on-site diagnosis
Upon our arrival, our technician carried out a complete inspection of the installation:
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verified supply voltage: 240 V stable;
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continuity of communication cables: correct;
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internal fuse of the control module: blown.
This initial finding already pointed the diagnosis towards a short circuit in the main electronic board . The unit also showed traces of humidity and dust near the control box - a common aggravating factor in older buildings.
Technical repair: fuse replacement and board test
1. Securing and dismantling
Before any work could be done, the circuit breaker was turned off and the front of the unit was completely removed. Condensate had leaked onto the board, probably from a clogged drain , creating long-term moisture buildup.
2. Cleaning and thorough inspection
We cleaned the components with dielectric contact spray to prevent corrosion, then tested the continuity of the traces on the board. A swollen resistance confirmed a previous surge. The main fuse (T3.15A) was replaced, followed by a no-load test.
3. Power on and performance test
The unit rebooted successfully. We then have:
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checked communication with the outdoor unit;
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tested the variable speed fan;
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measured the blowing temperature: 8.9°C for a room at 22°C — proof of restored performance.
The challenge: adapting an old building to modern HVAC requirements
Outremont is full of older homes where thick walls and imposing moldings often complicate cable routing. In this particular case, the refrigeration line ran high in the ceiling , protected by an exposed cable duct. While functional, this arrangement sometimes creates condensation points when it passes through uninsulated areas.
Our technicians added an additional insulating sheath above the moldings to prevent any risk of future condensation. This discreet intervention preserved the aesthetics of the space while ensuring the system's performance.
Result: comfort restored and installation secure
Once the Fujitsu wall-mounted air conditioner was put back into service, we carried out several complete operating cycles:
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stable cooling;
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ventilation speed modulated according to ambient temperature;
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no abnormal noise detected.
The client particularly appreciated the transparency of our diagnosis and the precision of the tests carried out on site — a trademark of AirGreen , recognized in Montreal, Laval, Longueuil, on the North Shore and the South Shore.
AirGreen Tips for HVAC Systems in Older Buildings
For homes like those in Outremont, built before the 1950s, it is essential to:
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annually check the condition of the condensate drains ;
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keep electronic cards away from moisture;
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protect communication cables from electrical interference;
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have the coils cleaned at least once a year.
These simple actions prevent the majority of breakdowns and extend the lifespan of Fujitsu, Midea, Gree or Sharp wall systems - all brands that we regularly maintain.
Expertise recognized throughout Montreal
At AirGreen, every service is documented, measured, and performed according to manufacturer standards. Whether your system requires a one-time repair or complete maintenance , our teams provide fast, clean, and guaranteed service throughout Greater Montreal.
AirGreen — Fujitsu wall-mounted air conditioner repair experts in Montreal, Laval, Longueuil, North Shore and South Shore.
We bring your HVAC systems back to life, even in the oldest buildings.