An aging system showing signs of fatigue
At AirGreen , we regularly work on Daikin wall-mounted air conditioners that have been installed for over ten years. These units, renowned for their reliability, however, require rigorous maintenance and electrical checks over time.
This service call, made in Brossard on the South Shore , concerned a first-generation Daikin wall-mounted unit that was no longer producing cold air, even in maximum cooling mode.
Initial diagnosis: a sensor and control board problem
Upon arrival on site, our technician noted that the wall unit appeared functional in appearance—light on, remote control responsive—but that the outdoor compressor was no longer starting . After some testing, we quickly suspected a communication problem between the indoor control board and the outdoor module .
The full diagnosis included:
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A check of the voltages at the output of the main board.
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Control of thermal sensors and their ohmic resistance.
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Visual inspection of the electronic board, which showed signs of slight oxidation due to ambient humidity.
The evaporator temperature sensor (thermistor) was returning inconsistent values, preventing the outdoor module from getting the correct reading to start the cooling cycle.
Technical intervention: sensor replacement and internal cleaning
To correct the situation, our team proceeded to:
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Complete power cut-off to avoid any electrical risk.
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Dismantling the front panel of the Daikin unit.
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Removal of the original temperature sensor , replaced with a Daikin compatible thermistor calibrated to the manufacturer's specifications.
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Thorough cleaning of the evaporator with a mild biocide product to remove dust and residue that had accumulated on the fins.
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Checking the condensate drains , often blocked on older models, to prevent any internal water leaks.
Once everything was reassembled, switching on the power confirmed a return to normal : the outdoor compressor started, the cold air flow became constant again, and the ambient temperature dropped by 3°C in less than 15 minutes.
Prevention and maintenance to extend lifespan
This type of breakdown highlights the importance of periodic maintenance of Daikin wall units :
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Have the coils and filters cleaned at least once a year.
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Monitor for unusual noises and temperature variations.
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Schedule preventive maintenance before each summer to avoid sensor or electronic card failures.
At AirGreen, we offer an annual maintenance program that includes a complete cleaning, electrical check, refrigerant pressure, and sensor calibration—a simple solution to avoid unexpected repair costs.
Results and customer satisfaction
The Brossard client immediately regained comfort after the intervention. His Daikin unit, despite its age, is now operating at full capacity, and we recommended preventive monitoring before the next hot season .
This intervention demonstrates how accurate diagnosis and targeted intervention can extend the life of a quality wall-mounted air conditioner without requiring a complete replacement.