A service call in the heart of Montreal
At AirGreen , we were recently called to repair a Midea heat pump installed on the flat roof of a residential building in the Ville-Marie sector of downtown Montreal. Despite the still-cool spring, residents noticed that the system was no longer responding properly: no heating, and a silent outdoor fan. A typical sign of an electrical or control problem with the condenser.
Initial diagnosis: a hidden electrical fault
On site, our technician quickly noticed that the Midea wall-mounted heat pump , connected to a disconnect box , was no longer receiving adequate power. Upon opening the service panel, he discovered an oxidized connection and a loose wire at the box's entrance—a common occurrence in installations exposed to wind, rain, and frost, especially on Montreal flat roofs.
We have proceeded to:
-
Complete check of the wiring between the main circuit breaker and the outdoor condenser.
-
Inspection of the internal electronic board , in order to rule out a short circuit or a defective relay.
-
Continuity test on power terminals and voltage check.
The verdict: poor contact at the power terminal was causing intermittent power outages.
Technical intervention: securing and making the power supply reliable
We replaced the damaged terminal and rewired it to CSA standards , using new connectors and weather-resistant wire nuts. The refrigeration line insulation was also repositioned and resealed to protect against water infiltration and heat loss.
A preventive cleaning of the electrical compartment and the fan was carried out to ensure optimal performance of the heat pump.
Reboot Test and Performance Verification
Once the repair was complete, we restarted the system. In heating mode, the Midea heat pump quickly reached a blower temperature of 38°C , confirming a return to normal performance. The defrost and ventilation cycles were also successfully tested.
The client, the building manager, appreciated the speed of intervention and the transparency of the diagnosis , two fundamental values at AirGreen.
Why this type of failure is common on flat roofs
Flat roof HVAC systems , typical of downtown Montreal buildings, are subject to difficult conditions:
-
Extreme thermal variations between winter and summer.
-
Constant humidity and water infiltration into electrical boxes.
-
Wind vibrations can loosen connections.
These factors can lead to minor but recurring electrical failures if maintenance is not regular.
We therefore recommend biannual preventive maintenance : one in the spring before the air conditioning season, one in the fall before heating.
Our practical advice to avoid recurrence
-
Visually check outdoor cables and boxes after each winter.
-
Clean the internal filters to avoid overloading the compressor.
-
Schedule an annual electrical inspection performed by a certified technician.
-
Ensure that refrigeration ducts are well insulated and protected from the sun.
These simple actions extend the life of your heat pump and significantly reduce the risk of breakdown.
Recognized expertise in Montreal and beyond
At AirGreen , we operate daily in Montreal, Laval, Longueuil, on the North Shore and the South Shore , for the repair of heat pumps, air conditioners and HVAC systems of all brands: Midea, Gree, Fujitsu, Sharp, Zephyr, Goodman , and many others.
Our mission: to ensure resident comfort and reliable HVAC systems , whether it's a downtown condo or a suburban home.
In conclusion
This intervention once again demonstrates the importance of rigorous maintenance and a quality electrical connection to avoid service interruptions. Thanks to our expertise, the Midea heat pump in this building in the Ville-Marie district is now working perfectly, ready to face future temperature fluctuations.