In a typical Plateau-Mont-Royal backyard, between brick walls and restricted spaces, we intervened to put back into service a Tosot wall-mounted heat pump (mini-split) installed on wall brackets, high up, in order to optimize ground clearance and protect the outdoor unit from snow accumulation and shocks.
Even when the equipment appears to be "working," a heat pump can lose significant performance without the customer immediately understanding the cause. In this case, the reported symptoms were clear: uneven cooling , longer cycles, and a feeling of comfort that was "less stable" than before, especially on more humid days.
Installation context: a demanding (but common in Montreal) location
The photo shows a Tosot outdoor unit securely fixed to metal brackets on a brick wall in a fairly confined area. This type of setup is common in urban environments.
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Limited access (narrow alley/inner courtyard), which complicates handling and maintenance
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Proper air circulation is essential : in a confined space, even the slightest obstruction can reduce efficiency.
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Presence of an electrical disconnect switch nearby (good practice for safety during interventions)
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Useful installation height, but requires structured and safe intervention (ladders, stability, work areas)
AirGreen diagnosis: understanding the loss of performance (beyond appearances)
On a wall-mounted heat pump, a drop in efficiency can stem from simple fouling… or a more serious refrigeration problem. Our approach was therefore methodical:
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Verification of operating parameters
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temperatures in air conditioning mode and heating mode
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stability of the regime, cycle duration, response to instructions
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Visual inspection of the outdoor unit
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condition of the grid and the heat exchanger (coil)
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vibrations, play in the supports, level and fixing
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condition of pipe passages (refrigerant lines) and protection
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Refrigeration controls
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Pressure/overheating readings (depending on conditions)
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search for signs of insufficient charging
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inspection of fittings (typical areas: flare fittings , vibration points)
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The verdict: a progressive micro-leak at a fitting , resulting in an insufficient refrigerant charge . As a result, the Tosot heat pump was functioning, but less efficiently , with longer cycles and a decreasing capacity.
Repair completed: a lasting correction, not a “quick fix”
To avoid the classic scenario of "we reload and it starts all over again", we proceeded as follows:
1) Security and access
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power off via the disconnect switch
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stabilization of the work area (high-rise urban installation)
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checking the fixings to avoid any tension on the pipes
2) Repair of the faulty connection
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targeted dismantling of the relevant fitting
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clean reassembly (cutting/deburring if necessary, reflaring with calibrated tooling)
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Reinstall with appropriate tightening torque (to limit recurrence)
3) Leak test and vacuum sealing
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leak test (standard testing procedure)
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Deep vacuum sealing to remove moisture and non-condensable
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vacuum stabilization (validation)
4) Recommissioning and full validation
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recharging in accordance with the device's requirements
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tests in air conditioning and then in heating
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behavior check (temperatures, pressure, noise, vibrations, cycles)
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Final environmental control: clearance, air circulation, stability on supports
Results: restored comfort and more stable operation
After the repair, the customer quickly noticed:
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a more direct and consistent cooling
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shorter and better controlled cycles (less “effort” to reach the setpoint)
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overall quieter and more stable operation
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A return to confidence: the machine is no longer "on the edge", it is returning to normal performance
In this type of intervention, the added value is not just to repair: it is to repair correctly , by eliminating the real cause and validating the performance on site.
What we take away from this (and what it avoids)
A Tosot wall-mounted heat pump installed in an urban environment can very well offer excellent performance, provided that:
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The connections must be impeccable and checked.
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the outdoor unit has sufficient clearance
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Maintenance should be carried out at the right pace (particularly in dusty backyards with pollen and debris).
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The installation on supports remains stable (vibrations = stress on the fittings)
This case in Plateau-Mont-Royal perfectly illustrates a reality: a small defect can create a great loss of comfort , without a complete breakdown… until the day it breaks down.