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Réparation d’une thermopompe murale Gree à Ville-Marie
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Repair of a Gree wall-mounted heat pump in Ville-Marie

A heat pump on a downtown rooftop fails to cool

In Montreal, rooftop installations are common, especially in downtown apartment buildings or condos. At AirGreen , we regularly work in these specific contexts, where access and exposure to the elements make HVAC systems more vulnerable.
Recently, our team was called regarding a performance issue with a Gree wall-mounted heat pump installed on the roof of a residential building in Ville-Marie .

Symptoms: Low efficiency and heat buildup

The customer contacted us after noticing that the air blown inside was lukewarm despite the thermostat being set at 20°C. Additionally, the compressor noise seemed louder than usual.
On site, our technicians immediately observed:

  • Condenser fins clogged with urban dust.

  • A deformed protective grille , restricting airflow.

  • Damaged insulation on refrigeration lines exposed to the sun.

These elements indicated a compressor overheating problem linked to poor heat dissipation.

Precise diagnosis: analysis of the refrigeration circuit and pressure tests

After securing access to the roof, we carried out a complete diagnosis :

  • Measurement of low and high refrigerant pressure .

  • Checking the compressor discharge temperature .

  • Test the electronic card to ensure correct modulation of the inverter.

Result: the system displayed too high a pressure , a sign of a clogged condenser.
The compressor had to work hard to maintain the refrigeration cycle, which caused intermittent shutdowns and increased energy consumption .

Intervention: cleaning, repair and re-insulation

We undertook a deep cleaning of the outdoor condenser , using a biodegradable product specially designed for aluminum surfaces.
Afterwards :

  • The protective metal grille has been straightened to restore proper airflow.

  • The bent fins were straightened using a condenser comb.

  • The insulation of the refrigeration lines has been replaced to protect the circuit against UV rays.

Finally, a full performance test was carried out: after restarting, the pressures stabilized, the compressor operated normally, and the internal blowing temperature dropped to 12°C — proof of restored efficiency.

Maintenance Tips for Rooftop Systems

Our technicians took advantage of this intervention to remind the customer that rooftop units are particularly exposed to:

  • Urban dust and plant debris.

  • The extreme temperature differences between winter and summer.

  • Water infiltration which can accelerate corrosion.

We therefore recommend:

  • A biannual cleaning of the condenser (spring and fall).

  • An annual inspection of wiring and insulation .

  • Check the fixings and supports to avoid excessive vibrations caused by the wind.

These simple measures significantly extend the lifespan of heat pumps installed on flat roofs or terraces.

Results: efficiency and comfort restored

Thanks to this intervention, the Gree heat pump regained its original efficiency. The interior cooling became stable again , the noise level decreased , and the electricity consumption dropped by almost 20% according to the customer's readings the following week.

This type of failure perfectly illustrates how neglected condenser maintenance can harm the overall performance of the system — especially in dense urban environments like Ville-Marie or the Plateau-Mont-Royal .

AirGreen expertise: reliability and performance in Montreal

At AirGreen , every HVAC system intervention is guided by technical rigor and transparency . Our certified technicians work on all major brands: Gree, Midea, Fujitsu, Sharp, Lennox, Trane, Zephyr and Bosch .

We offer:

  • Accurate and rapid diagnostics .

  • Parts that meet original specifications .

  • Durable repairs , guaranteed to industry standards.

We cover all of Greater Montreal , including Laval, Longueuil, the North Shore and the South Shore , so that every home enjoys optimal comfort, summer and winter.

AirGreen: the benchmark in wall-mounted heat pump repair in Montreal

Whether it's preventative maintenance , an urgent repair , or a complete HVAC system replacement , our mission remains the same: to provide fast, professional, and long-lasting service.

AirGreen is the guarantee of clean air and a controlled indoor climate , regardless of external conditions.