A service call in the middle of a Montreal winter
At AirGreen , winter service calls are often related to defrosting issues or reduced performance on wall-mounted heat pumps . This is exactly what happened in this duplex in Rosemont–La Petite-Patrie , Montreal, where a homeowner contacted us about a Gree heat pump that was no longer heating adequately despite an outdoor temperature of only -5°C.
Installed about five years ago, this single-zone unit served the ground floor and was intended to provide the main heating. The customer noticed that the unit was constantly alternating between blowing warm air and cooling air, while also building up a layer of ice on the outdoor unit .
Diagnosis: a system in protection mode
During our inspection, we found that the Gree wall-mounted heat pump was receiving power, but the compressor was shutting off prematurely . The outdoor unit, located on the north side of the brick building, was partially blocked by snow and dead leaves that had accumulated around the base.
The measurements carried out revealed:
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Abnormally low discharge temperature.
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Defective defrost sensor , indicating false values.
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Light soiling of the external battery.
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Outdoor fan operating at reduced speed.
In winter, an incorrect reading from the defrost sensor prevents the heat pump from performing a complete defrost cycle , causing ice to form on the fins and blocking airflow.
Step-by-step technical intervention
1. Manual defrosting and thorough cleaning
We started by turning off the system and gently defrosting the outdoor coil using a controlled jet of warm water under pressure . Once the ice was removed, we cleaned the coil with a specialized biodegradable detergent to restore heat transfer.
2. Replacing the defrost sensor
We replaced the faulty thermistor with an original Gree model, calibrated according to the series temperature curve. This part, although discreet, is crucial for the proper functioning of the Heat Pump mode in cold climates.
3. Reset and Performance Test
After replacement, we reset the control board and ran a full test cycle:
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Fluid compressor start.
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Automatic defrost triggered at -3°C after 35 minutes of continuous operation.
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Discharge temperature in heating mode: 47°C stable .
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Pressure and intensity in accordance with manufacturer's specifications.
Result: efficiency restored and comfort restored
As soon as the intervention was completed, the customer noticed a rapid rise in the interior temperature , with uniform heat distribution. The heat pump was once again operating silently and without excess electricity consumption .
We recommended:
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Preventive maintenance every fall , before the cold period.
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A minimum clearance of 60 cm around the outdoor condenser , especially on the blowing side.
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Installing a raised base to prevent snow accumulation.
AirGreen expertise in Gree wall systems
Gree wall-mounted heat pumps are renowned for their performance in the Quebec climate, but like any HVAC system, they require seasonal monitoring. At AirGreen, we have repaired hundreds of units of this brand in the greater Montreal area.
Our team is trained to intervene on:
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Refrigerant leaks (R410A, R32).
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Electronic card faults .
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Sensor and defrost problems .
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Complete pre- and post-winter interviews .
Each intervention is carried out according to RBQ and CCQ standards, with original parts and certified performance tests.
A local service for Montreal, Laval and the South Shore
Whether you are in Rosemont, Laval-des-Rapides, Brossard or Terrebonne , our mobile teams ensure a rapid response and an accurate diagnosis . We prioritize repair before replacement , when economically viable, in order to maximize the lifespan of your equipment.
At AirGreen, our mission is simple: to provide you with reliable comfort all year round , regardless of the make or model of your system.
Warning: Working on heat pump systems requires regulated refrigerant handling. Always entrust this task to a technician holding a refrigeration qualification certificate recognized by the CCQ .