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Réparation d’une thermopompe murale Midea à Rosemont–La Petite-Patrie
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Repair of a Midea wall-mounted heat pump in Rosemont–La Petite-Patrie

A delicate external intervention on an urban installation

At AirGreen , we often work in Montreal neighborhoods where HVAC systems are located in tight spaces. This service call in Rosemont–La Petite-Patrie perfectly illustrates this type of configuration: a Midea wall-mounted heat pump mounted on a metal bracket outside a brick building, near a Generac generator.

The customer contacted us after noticing an abnormal noise coming from the compressor and a drop in heating performance , despite mild outdoor conditions. The main challenge: determining whether the problem was with the compressor, the fan, or an electrical anomaly related to the proximity of the generator.

Initial diagnosis: analysis of electrical and mechanical interactions

Upon our arrival, we carried out a complete inspection of the exterior system :

  • Checked the heat pump and generator power wiring : no short circuits or direct interference, but insufficient grounding detected.

  • Measurement of compressor start voltages : unstable variations between 208 and 218 V, confirming a power supply imbalance.

  • Listen to the compressor : intermittent metallic noise, typical of a dirty or misaligned fan motor .

Through these tests, we were able to confirm that the failure was caused by a combination of a dust-blocked fan and a poorly insulated electrical connection .

Step 1: Secure and thoroughly clean the unit

Working approximately 2.5 meters above the ground, our technician first secured the area before opening the compressor housing. The following steps were performed:

  1. Complete power cut to prevent any generator-related voltage feedback.

  2. Clean the fan and outdoor coil using a gentle, low-pressure jet.

  3. Lubrication and realignment of the fan motor , the shaft of which showed slight lateral play.

  4. Re-doing electrical connections with heat-shrink tubing to eliminate any risk of voltage loss.

After this first intervention, the fan regained smooth and silent movement.

Step 2: Verification of the thermodynamic cycle

Once the outdoor unit was cleaned and powered back up, we restarted the system and observed the refrigeration pressures. Results:

  • Low pressure: 120 psi (stable)

  • High pressure: 370 psi (normal for heating mode)

  • Indoor blowing temperature : 38.6°C after 8 minutes of operation

These values ​​demonstrate that the heat pump has regained its optimal operating balance .

Step 3: Calibration and Prevention

We then configured the Midea control module to adjust the compressor start frequency and reduce sudden current draws, which are particularly important when a generator is installed nearby.

Finally, our technician recommended to the customer:

  • Maintain a minimum clearance of 60 cm between the heat pump and the generator to avoid recirculation of hot air.

  • To carry out a biannual cleaning of the outdoor coil .

  • Consider an annual electrical system check to prevent voltage imbalances.

Result: a quiet and efficient heat pump

After a complete restart, the Midea heat pump operated silently , without vibration, and regained its full heating capacity.
The customer, who was worried about having to replace the unit, was able to see that a preventive and targeted intervention was enough to restore the system's performance.

This service call demonstrates the importance of in-depth technical expertise when multiple electrical devices are installed in the same facility. Thanks to our experience, we were able to:

  • Eliminate the cause of the noise;

  • Stabilize the power supply;

  • Restore operation to Midea standards;

  • Ensure the safety of the installation, even near a generator.

AirGreen: HVAC expertise in the heart of Montreal

The typical brick buildings of Rosemont–La Petite-Patrie often present specific installation constraints. At AirGreen, we have developed unique expertise to effectively operate in urban environments : narrow facades, limited access, combined equipment (heat pump + generator + ventilation).

Our goal: to guarantee lasting comfort and maximum energy efficiency to our customers, whether in Montreal, Laval, Longueuil, on the North Shore or the South Shore .

AirGreen Air Conditioning & Heating – HVAC experts who combine safety, performance and precision with every intervention.