Recommissioning an aging wall system in a Montreal apartment
At AirGreen , we regularly receive service calls for older wall-mounted air conditioners , often installed for more than 15 years. This call, made in the Côte-des-Neiges–Notre-Dame-de-Grâce neighborhood of Montreal , concerned a yellowing wall-mounted unit, still functional but whose customer noticed a marked drop in performance and abnormal noise .
Context of the intervention
The owner of this property contacted us after noticing that the wall-mounted air conditioner was no longer adequately cooling the main rooms, even at full power. Additionally, an intermittent vibrating noise was coming from the indoor unit, accompanied by a slight smell of burning dust during the first few minutes of operation.
Our technicians quickly identified that it was an older model of mini-split wall-mounted air conditioner , probably Fujitsu or Sharp , dating from the early 2000s. Although these units are known for their robustness, regular maintenance is crucial to maintain their performance.
Diagnosis: Dust accumulation, unbalanced fan and dirty coil
After removing the front panel and filters, we discovered:
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A thick accumulation of dust on the exchanger fins.
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A slightly misaligned fan motor , causing noise at high speeds.
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A dislodged temperature sensor (thermistor) , giving false readings to the control module.
These elements explained the drop in efficiency and the temperature fluctuation felt by the customer.
Steps of repair and in-depth maintenance
Our team undertook a complete cleaning of the interior unit :
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Complete removal of the front casing and centrifugal fan .
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Gentle steam cleaning of coils to remove dust and mold.
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Blower motor straightening and balancing .
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Reinstalling the temperature sensor to its original position.
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Checking the condensate drain and disinfecting the collection tray.
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Communication test with the outdoor unit to ensure proper data exchange via the control cable.
Once the repair was complete, the unit was powered back up and tested over several cycles. The background noise disappeared, and the temperature returned to a stable level, with a difference of 10°C between the inlet and outlet air , demonstrating a return to optimal operation.
Result: restored performance and extended lifespan
Thanks to this intervention, the customer was able to keep his original unit without immediate replacement. This type of recommissioning often extends the lifespan of older air conditioners by several years, while improving indoor comfort and air quality.
AirGreen Tips for Older Wall-Mounted Air Conditioners
Our technicians recommend:
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Annual preventative maintenance including cleaning of the fan and coils.
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A thermistor check to avoid temperature reading errors.
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Vibration monitoring : Aging blower motors can unbalance wall supports and cause cracks in walls.
In some cases, when the motor or control board is defective and parts are no longer available, we suggest a complete replacement with a modern wall-mounted heat pump , which is much more energy efficient (R32, SEER greater than 20, Inverter technology).
AirGreen expertise at your service in Montreal and throughout Greater Montreal
At AirGreen, we specialize in the repair and maintenance of residential and commercial HVAC systems , regardless of the brand or year of installation. We operate in Montreal , Laval , Longueuil , on the North Shore and the South Shore , with certified technicians trained according to RBQ and CCQ standards.
Every service call is handled with care: accurate diagnosis, transparent explanations, and measurable results. Whether your system is recent or from a previous generation, we bring your HVAC systems back to life with rigor and expertise.
AirGreen – Air Conditioning & Heating: Expertise in repairing old wall-mounted air conditioners in Montreal.