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

Diagnosis and repair of a silent but inactive outdoor unit

At AirGreen , we were recently called to Beaconsfield , on the West Island of Montreal, for a problem with a Midea wall-mounted heat pump that had stopped responding. The customer had noticed that, although the indoor unit seemed to be operating normally (display lit, ventilation active), the outdoor unit remained completely silent . No compressor or fan noise, no sign of starting. A typical failure that requires a thorough electrical and electronic analysis .

Initial inspection: a step-by-step diagnosis

Upon our arrival, we conducted a thorough visual inspection of the Midea condenser installed on a rear balcony, typical of residential buildings in Beaconsfield. The installation, relatively new and well-maintained, showed no visible damage.

First observations:

  • The indoor unit responded to commands.

  • No error codes were displayed on the remote.

  • The outdoor unit was not powered despite a start signal.

  • The communication cables between the units appeared intact.

These symptoms pointed our diagnosis towards a control board or power supply problem .

Technical analysis: checking voltages and circuits

Using our professional multimeter , we checked the voltage between the communication and power terminals. We found:

  • Presence of 240 V at the main input of the condenser.

  • No voltage on the secondary circuit to the compressor and fan.

This indicated that the main control board was no longer relaying power to the components, confirming an internal failure of the electronic control module (PCB) .

We then removed the electrical compartment cover to examine the board. A slight blackening around a power relay was observed—a sign of overheating or a minor short circuit that had caused the relay to fail.

Intervention: replacement of the electronic module

Once the fault was identified, we undertook the complete replacement of the external control board with an original Midea part, ordered directly from the authorized distributor.
Here are the main steps of the intervention:

  1. Power off to secure the system.

  2. Removing the old electronic module , cleaning the connectors and checking the wiring.

  3. Installation of the new PCB board , calibrated and updated according to the manufacturer's recommendations.

  4. Power up and complete communication test between indoor and outdoor units.

  5. Measurement of refrigeration pressures to ensure the proper functioning of the thermodynamic cycle.

After a few minutes, the compressor kicked in, followed by the fan. The system resumed its normal cooling cycle with stable pressures and a steady airflow.

Result: stable performance and a satisfied customer

The Midea heat pump returned to full performance after the repair. The customer immediately noticed rapid and quiet cooling , just like the original. We also took advantage of the intervention to clean the outdoor coil and check the wall bracket fixings to ensure the safety and longevity of the installation.

Post-repair performance data:

  • Incoming/outgoing air temperature difference: 11.2°C

  • Low pressure: 118 psi

  • High pressure: 365 psi

  • Power consumption stabilized at 6.3 A , in accordance with specifications.

AirGreen Tips to Prevent Electronic Failures

Control board failures on wall-mounted heat pumps can be avoided by following a few best practices:

  • Install a surge protector to protect against power surges.

  • Ensure that the condensation drain does not overflow onto electrical components.

  • Avoid accumulation of dust and moisture around the condenser.

  • Have electrical connections checked once a year by a certified technician.

These simple steps will significantly extend the life of your HVAC system.

AirGreen: HVAC experts in Beaconsfield and throughout Greater Montreal

At AirGreen , we offer a complete HVAC system installation, maintenance and repair service for the most reputable brands: Midea, Fujitsu, Gree, Lennox, Zephyr, Sharp, Bosch, Trane and many others.
Our qualified technicians operate throughout Montreal, Laval, Longueuil, on the North Shore and the South Shore , guaranteeing fast, precise and long-lasting service.

Your Midea heat pump won't start or remains silent?
Contact AirGreen , your trusted HVAC expert in Montreal, for an accurate diagnosis and guaranteed repair , carried out according to the highest industry standards.