When a heat pump breaks down in the middle of a Quebec winter
In the middle of January, a homeowner in Saint-Bruno , on the South Shore of Montreal , contacted us urgently. His Gree central heat pump , installed on an exterior aluminum support, had stopped heating overnight. Despite active interior ventilation, no heat was diffusing into the house. A typical case of breakdown during periods of extreme cold , when every minute counts.
Diagnosis: identify the cause of the breakdown
Upon arrival, we conducted a thorough inspection of the outdoor unit , which was installed on a raised snow rack. At first glance, the unit showed signs of abnormal frost around the copper pipes and compressor. Our technicians immediately suspected a refrigeration or defrosting problem.
We checked the following points:
-
R-32 refrigerant pressure: slightly lower than normal.
-
Defrost sensor condition: oxidized, inconsistent signal.
-
Electrical wiring : presence of humidity and corrosion on certain connectors.
-
Main electronic board : traces of condensation and defective relays.
The analysis confirmed a double failure : an inoperative defrost sensor prevented the automatic defrost cycle, while a relay on the main board blocked the compressor.
Technical intervention: complete repair and return to service
Our AirGreen team has undertaken the following steps:
-
Complete cleaning of the electrical box to remove all traces of humidity and corrosion.
-
Replacement of the defrost sensor with an original Gree part, calibrated according to the compressor temperature range.
-
Repair of the electronic card relay using a new compatible module.
-
Refrigerant Charge Check : Partial recharge to bring pressure back to 135 psi, according to manufacturer's specifications.
-
Complete operating test of the heating/defrosting cycle, below -10°C outside.
In less than an hour, the heat pump resumed normal operation. The compressor ran continuously, defrosting was smooth, and warm air was once again circulating throughout the house.
Cause analysis and preventive advice
The failure was primarily due to prolonged exposure to moisture and a lack of winter maintenance. Even the best heat pumps, such as Gree models, can be affected when condensation freezes on sensors or electrical relays.
We therefore advised the client:
-
Have the system inspected before each winter to prevent corrosion or fouling of the sensors.
-
Maintain a minimum clearance of 45 cm around the unit to facilitate ventilation and defrosting.
-
Install a ventilated protective canopy to limit snow accumulation on electrical components.
Result: comfort restored and reliability assured
Thanks to this intervention, the client has regained complete thermal comfort in his Saint-Bruno home. His Gree heat pump, now refurbished, operates stably and efficiently, even during the harshest cold weather on the South Shore .
This repair perfectly illustrates AirGreen 's philosophy: combining technical expertise , rapid response , and transparency . Whether in Montreal , Laval , Longueuil , on the North Shore or the South Shore , we intervene to diagnose, repair, and optimize any HVAC system—from simple wall-mounted mini-splits to complex central systems.
Problem encountered: Defective defrost sensor and electronic card relay.
Solution: Replacement of components, cleaning of the housing, refrigerant recharge and complete calibration.
Result: heating restored, optimal performance and comfort assured despite the cold.