An urgent service call for a frosted and dirty outdoor unit
At AirGreen , we regularly work on wall-mounted heat pumps installed on balconies or in confined spaces, as is often the case in Lachine buildings. That day, our team was called by a customer whose Gree heat pump was no longer producing hot or cold air. The outdoor unit, installed under a balcony shelf, was literally covered in frost and dirt , a sign of a defrosting and ventilation problem.
The customer noticed that his device was making a dull noise followed by a complete shutdown, before restarting a few minutes later. This is typical behavior of an overloaded compressor or a clogged external heat exchanger .
First inspection: severe fouling and poor defrosting
Upon arrival, we found the outdoor unit heavily clogged with dust and nicotine deposits—made worse by the proximity of ashtrays and smoke residue. These contaminants had penetrated the coil, significantly reducing airflow and causing the compressor to overheat .
We also noticed that the defrost sensor was not responding properly: it remained stuck at a constant temperature, preventing the system from defrosting properly. This problem is common when the heat pump operates for several seasons without maintenance.
Symptoms noted:
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Outdoor condenser covered in dust and frost
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Ineffective defrosting
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Noisy and overheated compressor
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Very low thermal efficiency
Complete diagnosis: a double problem of probe and maintenance
Our technicians began by performing an electrical continuity test on the defrost probe and temperature sensor. The result: the probe displayed abnormal resistance, confirming that it needed to be replaced.
At the same time, a check of the R410A refrigerant revealed a slight lack of charge , probably caused by a micro-leak at a copper connection.
We have therefore established a comprehensive intervention plan :
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Replacing the defrost sensor .
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Complete cleaning of the condenser and evaporator.
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Checking and tightening refrigeration connections .
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Recharge the system with refrigerant according to Gree specifications.
Repair and deep cleaning
The first step was to remove the side panel to access the connections and defrost circuit. After replacing the faulty sensor, we performed a gentle high-pressure cleaning of the coil using a non-corrosive detergent designed for aluminum surfaces.
We then degreased the condenser fins and manually removed the dust and nicotine deposits accumulated between the slats.
Once the cleaning was completed, we carried out a partial recharge with R410A , while monitoring the operating pressure in real time.
Recommissioning and performance verification
Once the heat pump was reassembled, we ran a full defrost cycle to check the new sensor's responsiveness. The discharge and suction temperatures stabilized at perfect values:
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Discharge temperature: 45°C
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Suction temperature: 10°C
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Working pressure: in accordance with manufacturer's specifications
The customer immediately noticed the restored silence of operation and the rapid rise in interior temperature .
Results: Efficiency restored and preventive maintenance recommended
After our intervention, the Gree heat pump returned to near-original efficiency. Defrosting was now uninterrupted, and the compressor operated smoothly and stably.
We recommended that the customer schedule an annual professional service , especially given the unit's location on a balcony exposed to dust and smoke.
Regular cleaning of the outdoor condenser and periodic replacement of the indoor filters are essential to extend the life of this type of installation.
AirGreen: your HVAC partner in Lachine and Greater Montreal
This intervention demonstrates the importance of regular maintenance and accurate diagnosis . At AirGreen , we work on all brands of wall-mounted heat pumps and multi-zone systems , including Gree, Fujitsu, Midea, Sharp, Daikin, Lennox and Bosch , in Montreal, Laval, Longueuil, on the North Shore and the South Shore .
Our RBQ and CCQ certified technicians are trained to resolve any type of breakdown: leaks, electronic cards, compressors, defrosting or refrigerant problems.
Every AirGreen service call results in a reliable, high-performance, and durable unit—and a satisfied customer, ready to face the Quebec seasons in complete comfort.
AirGreen – Specialists in the repair and maintenance of wall-mounted heat pumps in Montreal and the South Shore
Performance restored, comfort regained, impeccable service.