A heat pump that stops heating in the middle of spring: AirGreen efficiency in Lachine
At AirGreen , we often receive calls in early spring, when HVAC systems are called upon for the first time after winter. This is precisely what happened in Lachine , in the west end of Montreal, where a customer contacted us about a Tosot wall-mounted heat pump that was no longer producing heat.
The customer noticed that despite the outdoor unit being on, no warm air was coming out of the indoor unit. The system seemed to be responding to the remote control, but without any real heat transfer. A typical case of an abnormal defrost cycle or refrigerant problem , as we regularly encounter.
Diagnosis: Loss of pressure and temperature sensor failure
Upon arrival, we carried out a complete inspection of the Tosot outdoor unit, which was securely mounted on wall brackets above the ground, protected from debris. After inspection:
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The compressor started correctly, but the refrigerant pressure was abnormally low.
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The discharge temperature sensor (thermistor) was sending incorrect data to the electronic module.
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The defrost mode was activating too frequently, preventing the heat pump from maintaining a constant temperature inside.
Our technicians confirmed that a micro-leak had occurred at the expansion valve connection—a minor fault, but one that causes significant performance losses in the medium term.
Repair steps: AirGreen precision and rigor
In order to restore system performance, our team performed the following steps:
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Safe recovery of R410A refrigerant still present in the circuit.
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Replacement of the temperature sensor with an original Tosot part, calibrated according to the manufacturer's specifications.
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Repair and resoldering of the copper connection on the liquid line.
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Complete vacuum to remove moisture and internal impurities.
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Recharge with R410A refrigerant to the exact nominal charge, verified by electronic scale.
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Complete performance test of compressor, fan and defrost cycle.
After these interventions, the heat pump resumed stable operation. The indoor blowing temperature quickly rose to 38°C, demonstrating optimal heat transfer.
Result: restored comfort and improved energy efficiency
The customer immediately noticed the difference. In less than an hour, the house was warm and comfortable again. The outdoor unit operated quietly, proving that the compressor was no longer straining unnecessarily.
We also carried out a preventive check of the wall brackets , an often forgotten but essential detail to avoid vibrations and extend the life of the compressor.
Before leaving, we recommended to the client:
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A complete annual cleaning of the indoor coil and fan.
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An inspection of the condensate drain before each summer season.
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Using the “Auto” mode to maximize the efficiency of the Tosot defrost cycle.
Recognized expertise on the South Shore and Greater Montreal
This intervention in Lachine is a good illustration of the AirGreen approach: an accurate diagnosis , a lasting repair , and an optimization of energy efficiency . Our expertise covers all major brands, including Tosot, Gree, Midea, Fujitsu, Sharp, and Daikin , and extends to all of Greater Montreal, Laval, the North Shore and the South Shore .
Every service call is an opportunity for us to demonstrate that local expertise makes all the difference. By choosing AirGreen, you benefit from:
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Certified technicians trained in the latest HVAC technologies.
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A transparent service , without hidden costs or vague estimates.
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Post-intervention follow-up , guaranteeing the durability of our repairs.
AirGreen: your comfort, our priority
A well-maintained Tosot wall-mounted heat pump can provide up to 12 years of consistent performance. Our mission is to extend this lifespan while maintaining your comfort at the highest level. Whether in Lachine , Montreal , Laval , Longueuil , or elsewhere in the region, we provide fast, thorough, and always courteous service.
At AirGreen, we repair more than just a device: we restore your peace of mind.