A service call during a heatwave on the West Island
It was on a particularly hot day that we were contacted by a customer from Pointe-Claire , on the West Shore of Montreal , about a breakdown of his Fujitsu wall-mounted air conditioner . The unit, installed for several years in a recent condo, was no longer producing cold air despite the “OPERATION” indicator being continuously lit. This type of symptom is typical of a communication problem or an interrupted refrigeration cycle , often linked to delayed maintenance or an electronic failure.
Our client, concerned about the rapid rise in indoor temperature, called on AirGreen for a rapid diagnosis and lasting repair.
Initial diagnosis: advanced fouling and a faulty control board
Upon our arrival, our technicians carried out a thorough inspection of the Fujitsu ASU12RLS3 series indoor unit, a model known for its reliability but sensitive to fine dust and voltage fluctuations. The findings were clear:
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The blower flaps were clogged, significantly reducing airflow.
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The evaporator coil had a thick layer of dust and mold.
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The “OPERATION” light remained steady, while the electronic board refused to enter cooling mode.
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Outside, the compressor would not start , although it was receiving the correct power.
Electrical readings helped identify the source of the problem:
a faulty indoor control board , unable to send the start signal to the outdoor unit. A classic on some generations of Fujitsu when the capacitors on the board lose their capacity over time.
Repair: refurbishment of the electronic card and complete cleaning
At AirGreen, we always prioritize targeted repairs and long-term prevention . After validating the quote, our team undertook a two-part intervention:
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Replacement of the original Fujitsu internal electronic card , reprogrammed to match the customer's configuration.
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Complete cleaning of the indoor unit , including:
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Complete disassembly of the front cover and shutters.
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Antibacterial cleaning of the coil and turbine fan.
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Application of a biodegradable disinfectant treatment.
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Checking the refrigeration circuit using an electronic pressure gauge: pressures compliant, no signs of leakage.
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Communication test between units (stable 12V DC signal).
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Restart and calibrate the system.
As soon as the intervention was completed, the wall-mounted air conditioner was blowing air at 8°C , ensuring even cooling in the main room of the condo.
Technical features of the Fujitsu model
The Fujitsu ASU12RLS3 is a 12,000 BTU wall-mounted air conditioner known for its energy efficiency and quietness. However, like many compact models, it requires regular maintenance to prevent:
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Ice formation on the evaporator.
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Random error codes caused by dirty sensors.
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Board failures due to the accumulation of fine dust and moisture in the electronics box.
Our technicians recommend to all Fujitsu system owners:
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A complete internal cleaning every 2 years , including the turbine and coils.
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Annual preventive maintenance in spring to maintain optimal energy efficiency.
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Leave the visible filters clean , but above all do not neglect the internal part of the coil - often a source of excess energy consumption.
AirGreen: HVAC expertise serving Montreal comfort
At AirGreen , we operate every day throughout Montreal, Laval, Longueuil, the North Shore and the South Shore to diagnose, repair and maintain Fujitsu, Gree, Sharp, Midea, Hitachi, Goodman and several other well-known brands wall-mounted air conditioners .
Our approach is based on:
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Accurate diagnostics , based on real electrical and thermal measurements.
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Genuine manufacturer parts for every replacement.
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A transparent and fast service , always with a clear explanation to the customer.
We know every device tells a different story—one of comfort restored, breakdown avoided, and extended performance.
Result: immediate comfort and restored efficiency
A few minutes after the repair, the owner confirmed that the interior temperature had returned to a comfortable level. The unit, quieter than before, displayed stable performance, with a smooth operating cycle and reduced power consumption.
Thanks to this intervention, the Fujitsu wall-mounted air conditioner has regained its original efficiency, ready to face the heat of the Montreal summer.