Emergency intervention on a faulty outdoor condenser on a flat roof
At AirGreen , we are regularly called to diagnose and repair HVAC systems installed on flat roofs, typical of residential and commercial buildings in Montreal. This time, our team was dispatched to Lachine to work on a Midea central heat pump , whose outdoor unit had a complete fan failure. The client noticed a complete stoppage of airflow and an abnormal increase in the compressor temperature , a clear sign of a mechanical failure in the ventilation system.
Diagnosis: A blocked condenser fan and compressor overheating
Upon arrival on the roof, our technicians conducted a complete visual inspection. The condenser fan, normally responsible for expelling heat to the outside, was motionless despite the cooling cycle having been activated.
After opening the side panel and testing the components, the diagnosis became clearer:
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Condenser fan mechanically blocked : bent blades and seized central shaft.
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Overheated motor coil , caused by repeated forced starting.
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Accumulation of dust and moisture near the control module.
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Starting capacitor losing capacity.
The system therefore suffered a double consequence: insufficient cooling and overloaded compressor , risking a more serious breakdown if not repaired quickly.
Repair: engine replacement and complete mechanical rebalancing
At AirGreen, we always prioritize lasting repairs over temporary solutions. The intervention was carried out in several precise stages:
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Safely shut off the power supply and check the circuit.
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Complete disassembly of the fan and inspection of the hub to identify the cause of the blockage.
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Replacement of the fan motor with an equivalent Midea model certified as genuine, with improved efficiency.
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Cleaning the condenser and fins with a non-corrosive cleaner to restore heat transfer.
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Replacement of the starting capacitor to ensure stable starting torque.
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Checking electrical connections and insulation testing.
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Complete system testing to confirm smooth and quiet blade rotation.
After restarting, the heat pump returned to an optimal cooling cycle , without vibration or excessive noise. The cooling pressures and electrical currents were measured and found to be in accordance with Midea specifications.
Result: restored energy efficiency and ensured compressor safety
The unit has resumed normal operation with:
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Constant and quiet airflow .
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A reduced discharge temperature , a sign of a compressor that is now well ventilated.
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Energy efficiency restored to almost 98% of its initial performance.
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A reduction in the risk of major compressor failure .
The customer immediately noticed improved indoor comfort , particularly in previously undercooled areas. This preventative repair avoided a complete compressor replacement, which would have been much more expensive.
AirGreen Tips: The Importance of Preventative Maintenance on Flat Roofs
Systems installed on flat roofs, like this Midea central heat pump , are exposed to demanding climatic conditions: wind, rain, dust and significant temperature variations. These factors accelerate the wear of motors and blades.
Our recommendations:
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Biannual inspection (spring and fall) to detect any anomalies.
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Regularly clean the fins to avoid overheating.
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Check the motor and start capacitor before each heating and cooling season.
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Lubrication and balancing of fans to extend their life.
Structured maintenance, such as that offered by AirGreen , not only helps maintain system performance, but also reduces energy consumption sustainably.
AirGreen expertise serving Montreal and the North/South Shore
Our team of RBQ and CCQ certified technicians operates in Lachine, Dorval, Saint-Laurent, Laval, Brossard and Longueuil , providing repair and complete maintenance of HVAC systems of all brands: Midea, Gree, Sharp, Lennox, Goodman, Trane and Bosch .
At AirGreen, every repair is carried out to the highest standards in the industry, with a constant focus on performance, durability and customer comfort.
We ensure that each system regains its original efficiency, while respecting Quebec's energy efficiency requirements.