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

Rapid diagnosis and effective intervention by AirGreen

At AirGreen , our mission is simple: to provide fast, reliable, and sustainable HVAC services throughout Greater Montreal. During this service call in Sainte-Dorothée, Laval , we were contacted by a customer regarding a Midea wall-mounted heat pump that was no longer heating efficiently as the cold season approached.

1. Initial observation: loss of performance and unusual noise

The customer contacted us after noticing that the outdoor unit of their heat pump no longer seemed to be generating heat and was producing an irregular metallic noise during the defrost cycle. The indoor temperature remained at 18°C, despite a constant heating demand.

Upon our arrival, we first carried out a complete diagnosis :

  • Checking refrigerant pressure ;

  • Inspection of the compressor and outdoor fan motor ;

  • Examination of the electronic card and electrical connections ;

  • Observation of the automatic defrost cycle.

2. Analysis: a defrosting problem linked to a defective sensor

Our measurements revealed that the refrigerant gas pressure was within the required limits, ruling out a leak. However, the outdoor coil temperature sensor was sending incorrect data to the circuit board, preventing the heat pump from properly triggering defrost. As a result, the coil remained partially frosted, blocking airflow and unnecessarily straining the compressor.

3. Solution implemented: replacement of the sensor and complete cleaning

We replaced the Midea defrost sensor with an original part, followed by a complete cleaning of the condenser and ventilation grille. Next, we:

  • Checked the continuity of the sensors with a multimeter;

  • Restarted the system in heating mode to test the complete defrost cycle ;

  • Measured discharge temperature and airflow to ensure optimal performance.

4. Result: comfort regained and efficiency restored

After the repair, the heat pump regained its full power. The customer immediately noticed stable and uniform heat , without any abnormal noise. We also explained the importance of annual maintenance to prevent fouling of the coils and premature aging of the sensors.

5. AirGreen Tips: How to Avoid Winter Outages

Our technicians always remind you that:

  • Cleaning the internal filter every two months extends the life of the system.

  • Preventative maintenance in the fall allows you to detect weak sensors or worn components before the cold weather hits.

  • A well-maintained heat pump consumes up to 25% less energy in heating mode.

6. Midea expertise in Laval and throughout Greater Montreal

At AirGreen, we are authorized Midea dealers and installers , which allows us to ensure repairs comply with manufacturer specifications and guarantee the reliability of the installed equipment. Our interventions cover Montreal, Laval, Longueuil, the North Shore and the South Shore , with technicians specialized in each make and model.

7. Assessment of this intervention

  • Device Type: Midea 12,000 BTU Wall-Mounted Heat Pump

  • Problem: Defective defrost sensor

  • Solution: Sensor replacement + complete cleaning + defrost cycle test

  • Result: Restored heating, optimal comfort, quiet operation

  • Location: Sainte-Dorothée, Laval

Thanks to our rigorous approach and our mastery of Midea products, we have once again demonstrated that a professional HVAC service is not just about repairing, but about optimizing the comfort and durability of the system .