An urgent service call in a typical Montreal duplex
At AirGreen , we are regularly asked to work on Daikin wall-mounted heat pumps , renowned for their performance and durability. This time, our team visited the Rosemont–La Petite-Patrie neighborhood in Montreal, where a customer contacted us about an intermittent heating and cooling problem .
The outdoor unit, mounted high on a brick wall, was no longer starting consistently. The customer had noticed that, despite the indoor unit working properly, the ambient temperature was fluctuating abnormally , making the space uncomfortable.
Diagnosis: A communication problem between the units
Upon our arrival, our certified technicians carried out a complete diagnosis:
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Supply voltage : correct, no input electrical problems.
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Inspection of interconnected wiring between units: slight oxidation of terminals at the outdoor unit.
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Compressor check : random start, audible current draw noise but no full start.
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Outdoor temperature sensor test : irregular signal detected on main board.
We quickly determined that the outdoor unit control board was no longer properly transmitting signals to the indoor board, causing the system to become out of sync.
Steps of repair
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Complete power cut for safety reasons.
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Disassembly of the Daikin outdoor unit to access the electronic board.
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Complete cleaning of oxidized terminals and replacement of damaged electrical connectors.
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Installation of a new Daikin control board , adapted to the heat pump model.
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Communication test between units after reassembly.
Once these steps were completed, the system resumed smooth and stable operation , with perfect communication between the two units.
Observed results
After the repair, measurements taken by our team confirmed:
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A constant blowing temperature of 11°C in air conditioning mode.
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Smooth compressor start-up , without electrical jolts.
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Stable interior temperature restored in less than 20 minutes.
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A reduction in outside noise , thanks to the realignment of the wall support and the complete cleaning of the condenser.
The customer, who used his Daikin heat pump for both heating in the winter and cooling in the summer, immediately noticed the difference in comfort.
Recommended prevention and maintenance
Daikin electronic boards are very efficient but sensitive to humidity, especially on exterior wall installations exposed to freeze and thaw cycles. To avoid this type of failure, we recommend:
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Annual preventative maintenance including cleaning of printed circuits and tightening of electrical connections.
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Applying a protective coating to exposed cards.
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Checking the drainage and insulation of the pipes to prevent any water infiltration.
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A complete inspection before severe cold or heat waves.
AirGreen expertise on Daikin wall systems
With our experience on Daikin, Gree, Fujitsu, Midea and Lennox wall-mounted systems , we offer accurate, fast and durable HVAC repair service. Each AirGreen technician has specialized diagnostic tools and certified parts to ensure compatibility and performance for each installation.
Our intervention in Rosemont–La Petite-Patrie perfectly illustrates our philosophy: combining technical rigor with a human approach . Each client benefits from comprehensive follow-up, a clear explanation of the problem, and recommendations tailored to the reality of their home.
Comfort rediscovered in the heart of Montreal
The repaired Daikin heat pump is now operating optimally, ensuring four-season comfort for the customer. At AirGreen, we continue to support our residential and commercial customers in Montreal, Laval, Longueuil, the North Shore, and the South Shore , with an ongoing commitment to quality, transparency, and reliability.