A typical service call in Laval: quick diagnosis and lasting solution
At AirGreen , we regularly receive calls from customers in Laval about wall-mounted heat pump failures occurring during the heating or cooling season. In this specific case, we were contacted by a homeowner in the Sainte-Rose neighborhood of Laval, whose Midea heat pump was no longer functioning properly. The outdoor unit would no longer start, and the indoor air remained lukewarm despite the heat demand.
The arrival of our team on site
Upon arrival, we noticed a Midea compact outdoor unit , installed on a wall bracket on the second floor. Access required the use of our telescopic ladder and a safety harness. The unit had noticeable fouling of the condenser fins , but more importantly, a loose temperature sensor , a common problem that can distort the temperature reading and disrupt the defrost cycle.
Fault diagnosis
After the electrical check (voltage, continuity, fuses), we tested the refrigeration circuit using our digital manifold. The compressor was receiving power, but the control board was not giving the start signal. We then discovered that the condenser thermistor (outdoor temperature sensor) was faulty—it was indicating an incorrect resistance value, which prevented the electronic board from starting the heating cycle.
This type of breakdown often manifests itself by:
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Quiet outdoor unit, even in heating mode.
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Indoor fan working, but lukewarm air.
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No error codes visible on the wall unit.
Repair carried out
We carried out a complete replacement of the outdoor temperature sensor , a genuine Midea part compatible with the customer's model. Before installation, the new sensor was tested with a multimeter to confirm the correct resistance value at room temperature. Once the part was replaced and correctly attached to the coil, we cleaned the condenser fins using a gentle spray and a biodegradable cleaner, then restarted the system.
A few seconds after powering up again, the heat pump started normally , the compressor started, and the fan resumed its automatic defrost cycle.
Results after intervention
Thanks to this quick and precise repair, the customer was able to regain optimal thermal comfort . Performance tests confirmed:
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Stable pressure on the high and low pressure sides.
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A discharge temperature in accordance with Midea specifications.
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Improved energy efficiency after sensor cleaning and calibration.
The customer particularly appreciated our speed of response (less than 24 hours after the initial call) and our clear technical explanations on the operation of the probe and the warning signs of a similar failure.
Recommended preventive maintenance
Upon our departure, we advised the client to have a full annual maintenance including:
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Cleaning the outdoor condenser and indoor evaporator.
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Checking temperature probes and sensors.
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Checking the insulation of exposed electrical cables .
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A pressure inspection to ensure the integrity of the refrigeration circuit.
This type of maintenance helps prevent breakdowns related to overheating or icing of the system, while maintaining high energy performance, essential for the harsh Laval winters and the humid summers of Greater Montreal.
A repair signed AirGreen
Each AirGreen intervention is carried out with the same rigor:
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Accurate diagnosis , based on professional measuring instruments.
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Exclusive use of original parts (Midea, Gree, Fujitsu, Sharp, etc.).
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Transparent service , with full explanation to the customer before any repair.
In Sainte-Rose , as elsewhere on the North Shore and throughout Montreal , we work on all makes and models of wall-mounted heat pumps , whether it is due to electrical failures, refrigerant leaks or defective electronic cards.
In conclusion
This Midea heat pump repair in Sainte-Rose perfectly illustrates our approach: expertise, precision, and attention to detail. Thanks to a targeted intervention, we revived a system essential to the customer's daily comfort, while extending its useful life.