When the reliability of a Carrier system meets the expertise of AirGreen
On the roof of a Pointe-Claire residence, our AirGreen team was recently called for a service call regarding a Carrier wall-mounted heat pump . This unit, installed on an upper deck, had stopped heating properly, leaving the owner uncomfortable during a particularly cold morning. A quick and accurate diagnosis was essential.
A careful diagnosis under demanding conditions
Upon arrival, we noticed that the Carrier outdoor unit , mounted on a wall bracket, had abnormal frost buildup on the evaporator fins. This symptom indicated a fault in the defrost cycle —a common problem on some wall-mounted heat pumps when a faulty sensor or control board prevents proper heat mode operation.
We started with:
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Check the voltage and continuity of the defrost sensors ;
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Inspect the electronic board for signs of moisture or corrosion;
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Analyze the R-410A refrigerant pressure to confirm circuit balance.
Measurements revealed that the compressor and fans were operating properly, but the defrost sensor was out of tolerance , preventing the heat pump from exiting the ice cycle.
Targeted and lasting repair
Our technicians replaced the defrost sensor with an original Carrier model, ensuring full compatibility with the existing system. A full defrost cycle was then forced to verify the control board's response and the return to heating mode.
At the same time, we cleaned:
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The fins of the outdoor unit;
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The condensate recovery tank;
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Electrical connections oxidized by exposure to salt and moisture.
The result was a smooth and stable restart of the system , with a delta T (incoming/outgoing air temperature difference) in line with Carrier's specifications. The heat pump returned to full heating capacity , and the customer was able to immediately appreciate the difference inside.
The Importance of Preventive Maintenance on Rooftop Units
Wall-mounted heat pump installations on roofs, like this customer's, are particularly exposed:
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To the cold winds which accelerate icing;
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To deposits of debris and dust which impair heat exchange;
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To constant humidity which can affect electronic boards.
At AirGreen, we recommend complete preventative maintenance twice a year : once before the heating season, and again before summer. This maintenance includes:
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Cleaning the condenser and evaporator;
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Checking refrigerant pressures and charge;
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Electrical and electronic inspection;
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Calibration of probes and sensors;
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Complete heating and air conditioning performance test.
This type of intervention considerably reduces breakdowns during critical periods and extends the life of the heat pump .
Why use AirGreen for your Carrier repairs in Montreal and Laval?
Our expertise covers all recognized brands on the market , and Carrier is one of the systems we regularly maintain and repair. Our trained and certified technicians ensure that each repair:
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Follows manufacturer protocols;
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Uses only genuine parts ;
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Aim for lasting performance, not just a temporary fix.
We respond quickly in Montreal, Laval, Longueuil, the North Shore and the South Shore , with fully equipped vehicles to diagnose and repair on site, even in the most demanding weather conditions.
Result: comfort restored and customer satisfied
Within minutes of restarting, the interior temperature had steadily risen, and the customer was able to return to comfort without delay. A simple fault in a small sensor could have turned into a prolonged outage without the prompt and professional intervention of our team.
This intervention demonstrates once again that the right diagnosis, the right parts and the right know-how make all the difference .
AirGreen , your Carrier heat pump repair specialist in Pointe-Claire and throughout Greater Montreal, remains your best ally for maintaining optimal comfort, winter and summer.