Repair of a Tosot wall-mounted heat pump in Le Plateau-Mont-Royal (Montreal)

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.

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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.

• Limited access (narrow alley/inner courtyard), which complicates handling and maintenance

• Proper air circulation is essential : in a confined space, even the slightest obstruction can reduce efficiency.

• Presence of an electrical disconnect switch nearby (good practice for safety during interventions)

• Useful installation height, but requires structured and safe intervention (ladders, stability, work areas)

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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:

1. Verification of operating parameters

   • temperatures in air conditioning mode and heating mode

   • stability of the regime, cycle duration, response to instructions

2. Visual inspection of the outdoor unit

   • condition of the grid and the heat exchanger (coil)

   • vibrations, play in the supports, level and fixing

   • condition of pipe passages (refrigerant lines) and protection

3. Refrigeration controls

   • Pressure/overheating readings (depending on conditions)

   • search for signs of insufficient charging

   • inspection of fittings (typical areas: flare fittings , vibration points)

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.

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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

• power off via the disconnect switch

• stabilization of the work area (high-rise urban installation)

• checking the fixings to avoid any tension on the pipes

2) Repair of the faulty connection

• targeted dismantling of the relevant fitting

• clean reassembly (cutting/deburring if necessary, reflaring with calibrated tooling)

• Reinstall with appropriate tightening torque (to limit recurrence)

3) Leak test and vacuum sealing

• leak test (standard testing procedure)

• Deep vacuum sealing to remove moisture and non-condensable

• vacuum stabilization (validation)

4) Recommissioning and full validation

• recharging in accordance with the device's requirements

• tests in air conditioning and then in heating

• behavior check (temperatures, pressure, noise, vibrations, cycles)

• Final environmental control: clearance, air circulation, stability on supports

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Results: restored comfort and more stable operation

After the repair, the customer quickly noticed:

• a more direct and consistent cooling

• shorter and better controlled cycles (less “effort” to reach the setpoint)

• overall quieter and more stable operation

• 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.

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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:

• The connections must be impeccable and checked.

• the outdoor unit has sufficient clearance

• Maintenance should be carried out at the right pace (particularly in dusty backyards with pollen and debris).

• 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.