A service call for a heat pump that was no longer heating
At AirGreen , we were called by a customer from Sainte-Julie , on the South Shore of Montreal , whose Tosot Inverter wall-mounted heat pump was no longer producing heat, despite the fan operating normally. This type of breakdown is quite common in the spring, when defrost cycles or compressor management become unregulated after a winter period.
The customer had already attempted a complete circuit breaker reset without success. When we arrived, the outdoor unit—securely mounted on the house's beige vinyl siding—was displaying flashing lights, indicating a communication error between the indoor and outdoor circuit boards .
In-depth diagnosis
Our certified technicians undertook a complete diagnosis of the Tosot system:
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Checking the supply voltage : normal and stable at 240V.
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Inspection of communication wiring between units: slight oxidation on one terminal.
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Inverter module analysis : irregular operation during start-up test.
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R-410A refrigerant pressure measurement : slightly below recommended values.
Using our digital diagnostic tools, we confirmed that the compressor control module (outdoor PCB) was damaged, likely due to an electrical surge combined with a slight loss of refrigerant.
Complete intervention and restoration
Once the cause was identified, we took the following steps:
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Replacement of the Inverter control module with an original Tosot part.
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Partial recharge of R-410A refrigerant to restore nominal circuit pressure.
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Complete cleaning of the outdoor unit using a low-pressure jet and a biodegradable product to remove dust and debris accumulated on the exchanger.
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Rebuilding electrical connections and applying a dielectric protective product to prevent future oxidation.
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Complete test in heating and air conditioning mode , over several cycles, to ensure the stability of the compressor and fan.
Results: performance and comfort restored
Once the repair was completed, the Tosot wall-mounted heat pump resumed perfect operation:
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Stable and uniform interior temperature.
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Smooth and quiet compressor start-up.
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Reduced power consumption, thanks to the precise regulation of the Inverter.
The satisfied customer regained optimal comfort in his home while avoiding the complete replacement of his appliance. We also recommended annual preventive maintenance , essential for Tosot, Fujitsu and Midea units to ensure the longevity of the electronic modules and the stability of the refrigeration pressures.
AirGreen expertise: a rigorous and human approach
Every AirGreen service is based on the same principle: understand the cause before replacing . Our technicians are trained to analyze every component of an HVAC system, whether it's a circuit board, a compressor, or a temperature sensor , in order to make an accurate diagnosis and avoid unnecessary costly repairs.
Our teams travel throughout Montreal, Laval, Longueuil, the North Shore and the South Shore , with fully equipped vehicles to work on major brands such as Tosot, Gree, Fujitsu, Midea, Sharp, Zephyr and Trane .
Maintenance tips for your Tosot heat pump
To ensure long-lasting performance and avoid recurring breakdowns:
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Clean the internal filters every month during the usage season.
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Monitor defrost cycles in winter: a heat pump that remains frozen for more than 30 minutes should be checked.
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Schedule a professional annual maintenance , including coil cleaning, pressure checking and inverter module calibration.
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Install a surge protector on the power line to protect Tosot electronic boards.
A sustainable repair by AirGreen
In just a few hours, our team transformed a faulty heat pump into a high-performance, quiet system ready to provide comfort and efficiency year-round. At AirGreen , we combine technology, rigor, and human service to ensure lasting interventions that meet the strictest standards in the HVAC field.