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Réparation d’une thermopompe murale Midea à Brossard
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Repair of a Midea wall-mounted heat pump in Brossard

AirGreen intervention on a flat roof: a safe technical repair

On the South Shore of Montreal , more precisely in Brossard , our team was called to work on a Midea wall-mounted heat pump installed on the roof of a residential building. The customer had noticed that the outdoor unit was no longer starting, despite a functional thermostat and a normal indoor display. In these situations, the cause is often linked to a power outage or a communication problem between the indoor and outdoor units.

At AirGreen , we are accustomed to this type of flat roof installation, typical of modern buildings in Brossard or Longueuil. These configurations require precise know-how, both for the safety of our technicians and for the protection of equipment exposed to the elements.

Diagnosis: Power supply failure detected

During our initial inspection, we conducted a complete analysis of the electrical circuit powering the heat pump. Our technicians quickly identified that the Milbank outdoor circuit breaker , mounted directly next to the unit, had advanced oxidation at the terminals . This corrosion was preventing power from properly reaching the compressor.

A multimeter check confirmed that 240V was not reaching the Midea unit, explaining the complete lack of power. This type of failure is common after several freeze/thaw cycles, especially on roofs exposed to wind and humidity.

Intervention: replacement of the circuit breaker and inspection of the wiring

Our experts undertook the complete restoration of the electrical circuit :

  1. Safe power cut-off from the building's main panel;

  2. Complete disassembly of the Milbank case and cleaning of the power cables;

  3. Replacement of the external circuit breaker with a corrosion-resistant CSA-compliant model;

  4. Continuity check on phase and neutral wires;

  5. Checking the Midea compressor and internal components (capacitor, relay, electronic board).

After power was restored, the unit began operating normally. The compressor started with stable amperage , and the discharge temperature reached its nominal values ​​after only a few minutes.

Result: restored performance and increased reliability

Thanks to this intervention, the Midea heat pump regained its full functionality. Warm air circulated throughout the home again, ensuring the customer's comfort despite the still-cool spring temperatures.

In addition to the repair, our technicians installed an additional waterproofing box and applied a dielectric sealant to prevent future water infiltration. This type of detail makes all the difference when it comes to ensuring the durability of a flat roof installation , which is often more vulnerable to the elements.

AirGreen Expertise: Safety, Precision and Sustainability

This repair showcases our technical expertise in Midea HVAC systems and our commitment to on-site safety. At AirGreen, each intervention follows a rigorous methodology:

  • Complete check of the electrical and refrigeration network ;

  • Use of calibrated and certified tools ;

  • Detailed service report provided to the customer;

  • Post-intervention monitoring to ensure system stability.

Our teams operate throughout Greater Montreal , including Brossard, Longueuil, Laval, Montreal and the North Shore , to ensure long-lasting repairs that meet the strictest standards.

Recommendations for Rooftop Unit Owners

  1. Visually inspect the outdoor circuit breaker twice a year.

  2. Avoid any accumulation of standing water around the base of the unit.

  3. Have the electrical connections checked before the cold weather or summer.

  4. Schedule a complete annual maintenance including coil cleaning and pressure testing.

  5. Install a cover to protect against rain and melting snow.

These simple precautions can prevent up to 80% of electrical failures observed on heat pumps installed at height.

AirGreen: Your HVAC Partner on the South Shore and Beyond

Whether it's for a Midea heat pump repair , preventative maintenance , or a complete installation , AirGreen provides you with a team of passionate experts.
We travel to Montreal, Laval, Longueuil, the South Shore and the North Shore , to guarantee fast, safe and sustainable service , in line with the expectations of owners and the requirements of the Quebec climate.