An urgent call in the middle of a summer afternoon
It's a typical call for our AirGreen team in Montreal : a Daikin wall-mounted air conditioner suddenly stops blowing cool air when the outside temperature exceeds 30°C. This time, the intervention took place in a bright apartment in the Rosemont–La Petite-Patrie neighborhood, where the customer noticed that the unit was working, but no longer producing any cooling.
Installed above a closet, the Daikin wall-mounted air conditioner was already showing signs of aging: yellowed filters, faint fan noise, and a flashing indicator on the panel. Our mission was clear: diagnose the problem, repair it efficiently, and restore the customer's comfort.
Diagnosis: A combination of clogged filters and a faulty temperature probe
Upon opening the hood, our technicians noticed a buildup of dust on the air filters and evaporator. This type of obstruction, common after several seasons without maintenance, prevents airflow and can force the compressor to shut down.
But the diagnosis didn't stop there. After a few operational tests, we noticed that the temperature detected by the indoor sensor remained stuck around 27°C, regardless of the actual temperature. This explained why the system refused to engage cooling mode: the control board was receiving incorrect information.
Using our measuring instruments, we confirmed that the thermistor (NTC sensor) , which measures the temperature of the incoming air, was defective.
The precise steps of the repair
Each AirGreen intervention follows a rigorous method, adapted to the model and condition of the system:
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Power cut-off to secure the intervention area.
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Remove filters and thoroughly clean with an antibacterial and biodegradable cleaner.
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Disassembly of the front panel and extraction of the internal temperature probe.
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Replacement with a new original Daikin sensor compatible with the model.
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Inspect the indoor fan to remove any dust buildup on the blades.
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Power up and complete test of the cooling cycle.
After the repair, the air conditioner restarted without any error flashing. We measured a difference of 11°C between the intake and exhaust air—proof that the compressor and evaporator were working optimally again.
Personalized advice for the client
Before leaving the premises, our technician took the time to share several simple but essential tips:
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Clean the filters every two to three weeks during the summer.
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Schedule an annual maintenance , especially before the hot season.
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Never obstruct the indoor unit (curtains, furniture, decorative objects).
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Use “Dry” mode in humid weather to avoid excessive condensation.
The customer also opted for our annual AirGreen maintenance plan , guaranteeing regular monitoring and priority in the event of a future breakdown.
AirGreen expertise in the Rosemont–La Petite-Patrie neighborhood
This case perfectly illustrates the added value of professional maintenance : rapid diagnosis, original parts, and a rigorous approach.
Our teams operate throughout Montreal, Laval, the North Shore and the South Shore , and are familiar with the specific features of older buildings like those in the Rosemont area — often equipped with wall systems installed over a decade ago.
From our experience, we know that a well-maintained Daikin wall-mounted air conditioner can provide up to 15 to 20 years of reliable service . In this case, the repair restored the unit to full efficiency, while avoiding premature replacement.
Conclusion
At AirGreen , every service call is an opportunity to demonstrate our expertise and attention to detail.
This Daikin wall-mounted air conditioner in Rosemont–La Petite-Patrie is now in perfect working order, and its owner once again enjoys ideal comfort, without noise or error flashing.
For any wall-mounted air conditioner repair, installation, or maintenance in Montreal, Laval, Longueuil, on the North Shore, or the South Shore , trust our team of certified HVAC experts. We ensure performance, durability, and your comfort—quite simply.