When an HVAC system refuses to start at the coldest time of year
At AirGreen , we often receive emergency calls at the end of winter, when heating systems are undergoing their final stress before spring. This is exactly what happened in Sainte-Thérèse , on Montreal's North Shore , where a customer contacted us because their Midea central heat pump was no longer starting. The outdoor unit, installed on a wooden deck, displayed an error light and was no longer responding to thermostat commands.
Our technicians quickly dispatched a team to the site to carry out a complete diagnosis and restore comfort to the home before the nighttime cold returned.
Initial diagnosis: an electrical fault masked by frost
Upon our arrival, we noticed several important elements:
-
The Midea heat pump's outdoor compressor was covered with a light layer of ice, indicating an inoperative defrost circuit .
-
A temporary extension cord had been used by the customer during a maintenance test—a detail that immediately caught our attention.
-
The indoor unit was working properly, but no signal was being received from the outdoor compressor .
After securing the power, our lead technician opened the heat pump's electrical panel. A quick check revealed a partially damaged control board , likely due to a power surge. This failure prevented the outdoor unit from receiving the compressor start command.
Intervention: repair of the outdoor module and complete check of the defrost cycle
In order to get the system back up and running, our technicians carried out the following steps:
-
Safe disconnection of the power supply.
-
Complete cleaning of the electronic compartment and power terminals.
-
Replacement of the control board with an original Midea part compatible with the customer's model.
-
Checking the automatic defrost cycle , essential to prevent ice buildup on the condenser fins.
-
Test the compressor at different speeds to ensure proper pressure balance in the refrigeration circuit.
Once the new board was installed and the circuit defrosted, the heat pump resumed normal operation. Warm air was once again circulating throughout the house, and the refrigerant pressure remained within the manufacturer's recommended ranges.
Maintenance and prevention tips for spring
Before leaving the premises, we shared some practical tips with the client:
-
Avoid using extension cords that are not suitable for the power of the heat pump.
-
Clean the area around the outdoor unit regularly to ensure good air circulation, especially in winter.
-
Schedule a complete service before the summer period, including checking the R-410A refrigerant level and the condition of the fan.
At AirGreen, we always emphasize the importance of annual preventative maintenance. This not only extends the lifespan of the system, but also significantly reduces energy consumption—a real benefit for residents of the North Shore , where temperature swings are significant between January and July.
Result: restored comfort and optimal efficiency
Thanks to our rapid response, the customer's Midea central heat pump is now operating at full capacity. Defrosting is automatic, the control board is calibrated, and the indoor temperature is once again stable and comfortable.
This type of repair highlights the technical know-how of our AirGreen teams , who are fully proficient in Midea, Fujitsu, Gree, Sharp, Goodman and Bosch HVAC systems, both for repair and maintenance.
We are proud to bring back to life equipment essential to the comfort of homes in Sainte-Thérèse , Montreal and the entire North Shore .
AirGreen — HVAC experts in Montreal, Laval, Longueuil, North Shore and South Shore.
For any emergency or preventative maintenance, contact our team today to ensure optimal performance of your HVAC system.