A service call under the Rosemère sun
On a hot summer day, our AirGreen team was called to work on a Midea wall-mounted heat pump installed on the flat roof of a residential building in Rosemère , on Montreal's North Shore. The customer, concerned that the indoor unit was no longer cool despite a seemingly functional outdoor unit, suspected a compressor failure or a lack of refrigerant.
This type of installation—an outdoor unit placed on the gravel of a flat roof —requires special attention: not only because of direct exposure to the sun, but also because of vibrations and the risk of water infiltration linked to an unsuitable support.
Diagnosis: Weakened performance and an overheated compressor
Upon arrival, we conducted a complete inspection of the heat pump. The Midea unit, with a capacity of approximately 12,000 BTUs , was exhibiting intermittent fan operation and abnormal suction pressure. Using our diagnostic instruments, we quickly confirmed:
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Insufficient refrigerant charge , probably due to a micro-leak in the refrigerant line;
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A buildup of dust and debris around the heat exchanger, significantly reducing thermal efficiency;
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A slightly oxidized electrical connection at the compressor terminal, causing intermittent loss of power.
These combined anomalies explained the loss of system efficiency and the overheating observed on the compressor.
Repair steps: rigor and precision signed AirGreen
At AirGreen, every intervention is carried out according to a strict protocol to ensure the durability and optimal performance of the HVAC system. Here are the steps we followed:
1. Complete leak test
We first located the leak using an electronic detector and confirmed its presence on a weakened solder joint near the condenser connection. After recovering the remaining refrigerant, we proceeded with a nitrogen and solder repair .
2. Thorough cleaning of the condenser
The outdoor coil was covered with a thin film of dust and gravel. We performed a low-pressure cleaning to restore full heat exchange capacity without damaging the fins.
3. Replacement of corroded electrical fittings
We disassembled and replaced the oxidized compressor terminal with a sealed waterproof connector , ensuring better electrical continuity and reducing the risk of long-term electrical arcing.
4. Recharging the refrigerant circuit
Once the system was evacuated, we recharged the heat pump with the precise amount of R410A refrigerant according to Midea's manufacturer's specifications. The discharge pressure and temperature were then adjusted until the nominal values were reached.
5. Checking the roof support
We found that the unit was resting directly on concrete slabs. Although stable, this mounting promotes water accumulation and deterioration of the gravel. We therefore recommended the client the future installation of an aluminum raised support , allowing better air circulation and extending the life of the roof.
Results: efficiency restored and comfort restored
Following these repairs, the Midea heat pump returned to optimal operation. Our performance measurements showed a blown air temperature of 8°C in cooling mode, in line with the manufacturer's standards. The customer immediately noticed a significant improvement in indoor comfort.
Additionally, the unit's power consumption has returned to normal, indicating that the compressor is no longer overloaded . Through rigorous maintenance and our expertise, we prevented the owner from experiencing a complete breakdown that would have required system replacement.
AirGreen Tips for Extending the Life of a Flat Roof Heat Pump
Rooftop installations require increased vigilance. Here are our recommendations:
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Inspect refrigeration connections annually for micro-leaks;
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Clean the condenser at least twice a season;
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Check the level and stability of the support after freeze-thaw periods;
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Avoid the accumulation of debris or gravel around the unit;
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Schedule annual preventative maintenance with an AirGreen certified technician.
These simple actions help prevent costly breakdowns and ensure optimal energy efficiency, even in the most demanding conditions of the Quebec climate.
Conclusion: AirGreen, the benchmark in HVAC repair on the North Shore
This intervention in Rosemère perfectly illustrates our approach: rigorous diagnosis, lasting repair and personalized support . At AirGreen, we do everything possible to ensure that each client quickly regains comfort and peace of mind, no matter the complexity of the problem.
Whether your heat pump is installed on a flat roof, a balcony or a backyard, our team serves all of Greater Montreal, Laval, the North Shore and the South Shore with the same professionalism and technical rigor.