Home » Some of Our Service Calls in Greater Montreal » Repair of a Midea wall-mounted air conditioner in Sainte-Thérèse
Réparation d’un climatiseur mural Midea à Sainte-Thérèse
Reading time: 4'

Repair of a Midea wall-mounted air conditioner in Sainte-Thérèse

A wall-mounted air conditioner that doesn't work during a heatwave: a quick intervention by AirGreen

A customer living in Sainte-Thérèse , on Montreal's North Shore , contacted us urgently: their Midea wall-mounted air conditioner had stopped working. No indicator lights, no airflow—complete silence. In periods of intense heat, a complete breakdown like this can quickly make the indoor environment uncomfortable.

At AirGreen , we know how essential a reliable HVAC system is, so our team arrived on-site the same day to diagnose and repair the faulty wall unit .

Step 1 – Complete electrical diagnosis

Upon opening the front panel, our technicians noticed several important clues:

  • The indoor unit showed no power ;

  • A loose communication wire was hanging outside the box, indicating a broken connection ;

  • The terminal's protective cover had been partially removed, leaving the cables vulnerable to moisture and vibration.

Using a multimeter, we confirmed that the voltage was not reaching the unit's circuit board. The fault was therefore due to a wiring fault between the indoor unit and the outdoor condenser .

Step 2 – Check the communication circuit and internal fuse

Midea wall-mounted systems use three-wire wiring (communication, power, and neutral). Upon inspection, we found:

  • A severed communication wire inside the wall conduit;

  • A blown thermal fuse on the main board, a result of the momentary short circuit.

This double failure explained why the device was completely unresponsive.

Step 3 – Repair and Recommissioning

Our technicians carried out the following operations:

  1. Replacing the internal fuse of the control board;

  2. Renovation of wall wiring , with soldering and heat-shrink tubing to ensure lasting insulation;

  3. Cleaning the connection terminal to remove traces of oxidation;

  4. Restoration of the protective cover and secure fixing of the wires ;

  5. Communication test between units via standard Midea protocol (stable signal at 230V).

Once the repair was complete, the wall unit immediately turned back on. The shutters opened, and a breath of fresh air was felt.

Step 4 – Checking overall operation

We ran a full cooling cycle to ensure all components were operating optimally:

  • Indoor fan : smooth rotation, no abnormal noise;

  • Outdoor compressor : soft start, no surge;

  • Blowing temperature : measured at 9.2°C , confirming good cooling efficiency.

The client thus found immediate comfort in his main room.

Cause analysis and prevention

This fault illustrates a common problem: a loose cable or one damaged by vibrations , often as a result of an initial improper installation or a temporary connection during a renovation . The electrical wires of wall-mounted air conditioners must always be protected in a rigid sheath or a waterproof wall conduit to prevent movement or pinching.

Our recommendations to the client:

  • Have the electrical connections inspected every spring before starting the appliance;

  • Never handle the visible wires of the indoor unit;

  • Use a certified technician for any addition or relocation of HVAC wiring.

AirGreen Expertise: a rigorous and sustainable approach

Every service call at AirGreen is based on a comprehensive diagnostic protocol:

  • Electrical and electronic verification;

  • Mechanical and thermal control;

  • Validation of communications between indoor and outdoor unit boards;

  • Final performance measures.

This method not only guarantees effective repair , but also prevention of future breakdowns .

Our technicians, trained in Midea, Fujitsu, Lennox, Gree, Mitsubishi, Sharp, Zephyr and several other brands, respond quickly throughout the Greater Montreal region, Laval, Longueuil, the North Shore and the South Shore .

Result: comfort restored and reliability assured

The intervention in Sainte-Thérèse was successfully completed. The Midea wall-mounted air conditioner is now working perfectly, delivering consistently cool and quiet air. The customer appreciated the speed and transparency of our approach, as well as the detailed explanations provided on-site.

In just a few hours, AirGreen brought a seemingly out-of-service system back to life, while ensuring a safer and more durable installation.

In summary

This case illustrates the importance of a thorough electrical inspection during a complete breakdown of a wall-mounted air conditioner. Thanks to a targeted and methodical repair , our team allowed this Sainte-Thérèse customer to regain comfort without having to replace his unit.

AirGreen , your reference in HVAC system repair and maintenance in Greater Montreal, combines technology, precision and reliability to ensure your air conditioner always operates at its best.