Repair of a Midea wall-mounted heat pump in Saint-Lambert

A specific service call for a newly installed wall unit

At AirGreen , we work daily on residential HVAC systems throughout the Greater Montreal area. Recently, our team traveled to Saint-Lambert , on the South Shore of Montreal , to resolve a problem encountered with a Midea wall-mounted heat pump .
The customer had just had their unit installed, but the initial start-up was interrupted: the indoor unit refused to start properly , the shutters would not open, and a slight clicking noise was heard when attempting to start it.

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Diagnosis: An internal power supply and control board problem

Upon arriving on site, our technician immediately noticed that the indoor unit was still partially covered with the factory protective film . This often trivial detail indicated that the system had probably not yet operated stably since the initial installation.

After a complete visual inspection, here are the points observed:

• Top cover not properly secured — sign of recent handling.

• Control wiring not properly seated on the main terminal.

• Electronic board (PCB) not powered — no voltage measured at terminal CN2.

• No communication signal between the indoor unit and the outdoor compressor.

The team then undertook a complete diagnostic using a current clamp and a multimeter , in order to confirm whether the internal power supply board was receiving the necessary voltage from the external module.

Result :
A poor contact on the communication cable connection (terminal S1-S2-S3) prevented two-way communication between the two units. This type of problem, although minor, completely prevents the system from functioning.

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Intervention: reestablishment of connections and complete calibration

Our technicians have carefully:

1. Removed the wall unit from the bracket to access the internal terminal blocks.

2. Cleaned the terminals and tightened each connection screw with a calibrated torque wrench.

3. Checked the polarity and voltage between terminals S1-S2-S3.

4. Reset the PCB via the main capacitor full discharge procedure.

5. Correctly repositioned the front panel , ensuring a watertight closure of the housing.

Once these steps were completed, the Midea heat pump was restarted in test mode. After a few seconds, the shutters opened , the fan started and the blown air quickly reached 18°C ​​in air conditioning mode .

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Results: A fully operational Midea system again

Thanks to this intervention, the heat pump has regained stable and silent operation.
The relieved customer was able to see:

• Immediate response from the remote control ,

• Even air circulation in the room ,

• No vibration or background noise.

Our technicians then took the time to carry out a complete calibration of the temperature sensor and a check of the condensate drainage , guaranteeing optimal long-term performance.

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Maintenance tips to avoid similar breakdowns

To avoid any startup or communication issues in the future, we recommended that the customer:

• Visually check the indicator lights on both units once a month.

• Never leave plastic film or packaging on an operating unit.

• Have a complete annual maintenance performed before each heating or cooling season.

• Entrust the verification of electronic cards only to a certified technician.

These simple actions help extend the lifespan of Midea appliances, renowned for their reliability and energy performance when properly maintained.

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AirGreen expertise: rigor, precision and guaranteed service

Every AirGreen service call is treated with the same level of attention.
In Saint-Lambert, as elsewhere on the South Shore, our teams of technicians specializing in residential and commercial HVAC systems respond quickly to:

• Diagnose any type of breakdown on wall-mounted or central heat pumps ,

• Repair electronic cards, compressors, fans or sensors ,

• Carry out certified installations that comply with CSA and RBQ standards ,

• Provide complete and transparent monitoring to each client.

This rigor allows us to ensure lasting efficiency and optimal comfort in each home served.

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Conclusion: professional service in the heart of the South Shore

The intervention in Saint-Lambert perfectly illustrates our commitment: a methodical diagnosis, a lasting repair and impeccable customer service.
Thanks to our expertise in Midea , Fujitsu , Gree , Sharp , and many other products, AirGreen remains an essential reference for all wall-mounted heat pump repairs in the greater Montreal, Laval, Longueuil, North Shore and South Shore areas.