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Réparation d’une thermopompe murale Midea à Côte-des-Neiges–Notre-Dame-de-Grâce
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Repair of a Midea wall-mounted heat pump in Côte-des-Neiges–Notre-Dame-de-Grâce

A service call in the middle of summer for a device at height

At AirGreen , we often receive urgent calls during Montreal heat waves. That day, in Côte-des-Neiges–Notre-Dame-de-Grâce (NDG) , our team intervened to diagnose a Midea wall-mounted heat pump installed high on a brick wall—a configuration typical of Montreal plexes.

Context of the intervention

The owner contacted us after noticing that the indoor unit was no longer blowing cold air, despite the thermostat being set at 20°C. The outdoor unit, securely mounted on a metal wall bracket more than two meters above the ground, seemed to be working intermittently: the fan would randomly stop and the expelled air would be lukewarm.

The elevated location made accessing the compressor difficult, but our AirGreen team has all the necessary equipment— telescopic ladders, handheld diagnostic tools, and precise measuring instruments —for this type of installation.

Step 1: Visual Inspection and Initial Checks

Upon our arrival, we carried out a thorough inspection :

  • Observation of the LED indicators of the outdoor unit: a repetitive flashing indicated a communication error between the indoor and outdoor modules.

  • Checking the electrical connections at the external terminal: slight oxidation on a signal connector.

  • Supply voltage measurement : correct at 240 V, excluding a power supply failure.

  • Fan observation : irregular start, sometimes stuck in pause mode, suggesting a problem with the electronic card or a defective relay .

Step 2: Detailed electronic diagnosis

We then connected our Midea diagnostic tool, allowing us to analyze the behavior of the outdoor module.
Result: error code E1 , typical of a loss of communication between the master and slave cards.

After removing the top cover, we identified:

  • A slightly oxidized main board at the CN3 connector.

  • Presence of residual moisture due to rainwater infiltration (the original installation did not include a protective gutter above the unit).

Step 3: On-site repair and performance testing

To fix the problem:

  1. We cleaned and dried the connectors with compressed air.

  2. Applied a dielectric protective coating to prevent corrosion.

  3. Tightened the internal wiring and replaced a worn female connector.

  4. Tested inter-card communication after full reset.

Immediate result: the heat pump restarted without error. The compressor started in less than 40 seconds, and the fan returned to its nominal speed.

We then measured:

  • Indoor blown air temperature: 11°C.

  • Inlet/outlet temperature difference: 9°C.

  • Discharge pressure meets Midea specifications .

Step 4: Installation optimization and prevention

As the heat pump was installed under an exposed metal staircase, we recommended:

  • The addition of an aluminum deflector to divert rainwater runoff.

  • Annual maintenance with cleaning of the coil and checking of the electronic card.

  • Check the wall bracket to prevent corrosion, as moisture often accumulates in these configurations.

Result: immediate comfort and peace of mind

In less than an hour, the Midea system was back to full performance. The customer, who had been suffering from stifling heat in his apartment, felt fresh, constant air immediately after the intervention.
We have also recorded the unit's serial number for automated annual maintenance tracking .

Why Midea Heat Pumps Require Special Attention

Midea units are renowned for their reliability, but like any wall-mounted electronic system exposed to the elements, good protection against moisture is essential.
Even minimal water infiltration can cause intermittent failures that are difficult to diagnose.
At AirGreen , our technicians trained in brands like Midea, Fujitsu, Gree, Sharp and Zephyr are fully familiar with the diagnostic protocols specific to each manufacturer.

In summary

  • Problem : Loss of inter-card communication due to water infiltration.

  • Solution : cleaning, drying, insulation and dielectric protection.

  • Result : complete reboot, optimal cooling, satisfied customer.

Thanks to a quick and methodical intervention, we brought this Midea wall-mounted heat pump in NDG back to life, once again demonstrating the rigor and know-how of AirGreen , your trusted HVAC partner in Montreal, Laval, Longueuil, the North Shore and the South Shore .