Internal fault detected in the middle of summer
At AirGreen , we recently received a service call for a Midea wall-mounted heat pump installed in a residence in Ville Mont-Royal , in the center of the island of Montreal. The customer reported a sudden interruption in cooling accompanied by a flashing light on the indoor unit. Despite several restart attempts, the heat pump refused to produce fresh air.
This type of symptom is common following a failure of the communication module between the indoor unit and the outdoor compressor. We therefore dispatched an emergency team to restart the system before the expected rise in temperatures for the week.
Step One: Inspect the Indoor Unit
Upon arrival, we visually inspected the Midea wall unit. The front panel had already been partially removed by the customer, revealing the evaporator coil. The unit displayed an “E1” error code, typical of a signal loss between the main board and the outside.
Using a multimeter and an infrared thermometer, our technicians confirmed:
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a stable 240V power supply on the outdoor unit side;
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a missing signal on the communication terminal;
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a shorted evaporator temperature sensor .
The diagnosis therefore pointed to a faulty internal electronic board , a failure often caused by electrical fluctuations or excessive humidity accumulated near the control board.
Disassembly and testing of the electronic circuit
We carefully disassembled the Midea main board located behind the side panel. Upon inspection, a trace of corrosion was detected on a signal connector. This oxidation prevented the proper flow of current between the sensors and the control module.
Repair steps:
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Thorough cleaning of the board using a specialized dielectric cleaner .
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Replaced the corroded connector with a new insulated terminal block.
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Checking signal continuity on the communication line.
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Soft restart with a synchronization test of both units (indoor/outdoor).
After restarting, the system correctly recognized the compressor signal, and the heat pump resumed a stable cooling cycle .
Additional maintenance: cleaning and calibration
Taking advantage of the intervention, our team:
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Cleaned the evaporator fins with a mild biodegradable solution;
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Blown out the condensate drain , often neglected and prone to blockages;
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Recalibrated the indoor temperature sensor , ensuring an accurate reading for comfort monitoring.
These operations not only restored the system's operation, but also improved energy efficiency and extended the device's lifespan.
Result: comfort restored to Town of Mount Royal
Within minutes of restarting, the customer noticed rapid cooling and perfect temperature stability in the main room. The interior noise level had returned to a quiet level, indicating that the fan and sensors were once again working in sync.
The client, impressed by the speed of our diagnosis and the precision of the intervention, chose to add an annual AirGreen maintenance contract to avoid any recurring problems.
Lessons from this intervention
Midea heat pumps , while efficient and effective, have sensitive electronic boards that must be protected from moisture and dust. At AirGreen, we recommend:
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to clean the filters every two months during the summer season;
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to have the cards inspected at least once a year;
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to install a surge protector to prevent electrical damage.
AirGreen Expertise: a reliable and local service
Thanks to our certified technicians specialized in Midea HVAC systems , we intervene every day throughout the greater Montreal region, Laval, Longueuil, the North Shore and the South Shore . Whether it is a refrigerant leak, an electronic breakdown or simple preventive maintenance , our interventions are fast, rigorous and guaranteed.
At AirGreen, our priority is simple: restore your comfort, protect your investment and ensure the longevity of your heat pump .