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Réparation d’une thermopompe murale Tosot à Rosemont–La Petite-Patrie (Montréal)
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Repair of a Tosot wall-mounted heat pump in Rosemont–La Petite-Patrie (Montreal)

When a heat pump starts blowing lukewarm air, making more noise than usual, or going into protection mode for no apparent reason, the problem isn't always major… but it needs to be diagnosed methodically. This intervention, carried out in Rosemont–La Petite-Patrie, perfectly illustrates what is often seen on a Tosot wall-mounted heat pump (compact outdoor unit with inverter technology, typical residential mini-split format).

On site, the outdoor unit is mounted on wall brackets , flush with a brick facade , with adequate lateral clearance and refrigerant piping (connections) running down the wall. This type of configuration is common in Montreal: efficient and discreet, but more susceptible to vibrations, micro-leaks at the connections, and dirt accumulation (dust, pollen, debris, etc.).

System type and model (realistic deduction)

This is a Tosot wall-mounted (mini-split) heat pump with Inverter technology.
The exact model is not legible in the photo, so we remain consistent and realistic: Tosot Inverter wall-mounted heat pump – residential series (Lomo type/equivalent) , single-zone (one indoor unit connected to this outdoor unit).

Symptoms reported by the customer

The client described a very classic scenario to us:

  • Less stable heating (warm air at times)

  • short cycles (stops/restarts),

  • vibrations perceptible against the wall,

  • yield was lower than usual on colder days.

These symptoms can have several causes: air restriction , fan problem , sensors , poor refrigerant charge , or micro-leak at a fitting (flare), especially on a wall installation where vibrations and temperature variations work on the seals.

AirGreen diagnosis: step by step (without guesswork)

We always proceed in a logical order, to avoid replacing parts unnecessarily:

  1. Visual and mechanical inspection

  • Checking wall supports , anchor points and anti-vibration pads (often crushed or insufficient over time).

  • Checking the condition of the coil and the air inlet/outlet: an accumulation of dust can reduce airflow and increase pressures.

  • Fan check: play, friction, signs of impact (small debris, ice, branches, etc.).

  1. Electrical measurements and operation

  • Reading operating parameters (Inverter), checking protections, observing behavior during start-up and stabilization.

  • Checking voltages/connections and the general condition of the wiring.

  1. Refrigeration control

  • Measurement of pressures and temperatures in stabilized regime (heating), comparison with normal operation.

  • Targeted leak detection at sensitive points: flare fittings , valves, connections, and areas close to vibrations.

Problem identified

In this specific case, we identified two contributing factors:

  • Vibrations and resonance on wall supports : the supports transmitted the vibration to the wall, which amplified the noise and could, in the long run, weaken some of the fittings.

  • Micro-leak at a fitting (flare) / slightly insufficient charge : nothing spectacular, but enough to degrade efficiency and cause less stable cycles, especially in heating.

This kind of situation is typical: the machine can "work", but less well , and the user mainly experiences a decrease in comfort and an increase in noise.

Repair completed (full and clean intervention)

To restore the Tosot system to optimal operation, we carried out the following:

  1. Mechanical stabilization

  • Re-establishing the fixation points and correcting the support.

  • Addition/optimization of suitable anti-vibration pads (the objective: to cut off transmission to the wall and protect the connections).

  1. Refrigeration correction (professional method)

  • Repair of the suspect fitting: cleaning, inspection, appropriate tightening torque.

  • Leak test (pressure testing) to confirm the correction.

  • Rigorous vacuuming to eliminate moisture and contaminants.

  • Adjusting the refrigerant charge according to best practices (without “charging by feel”), in order to restore stable pressures and temperatures.

  1. Cleaning and performance restoration

  • Targeted cleaning of the outdoor unit area (airflow).

  • Checking the defrost mode (important for heating in Montreal) and validating the cycle.

Result: restored comfort, reduced noise, stabilized performance

After repair:

  • The system has regained a quieter operation (noticeable reduction in resonance).

  • The heat pump maintains its setpoint better , with more stable cycles.

  • Heating efficiency has returned to a normal level, which often results in an immediate feeling of comfort and more logical consumption.

The customer noticed two things in particular immediately after the intervention: less vibration and more constant heat .

What we recommend to prevent it from happening again

For a Tosot wall-mounted heat pump installed on wall brackets (very common in Montreal), we recommend:

  • periodic cleaning of the filters (indoor unit) and an annual check of the outdoor coil,

  • an inspection of the anti-vibration mounts and pads (they wear down over time),

  • monitoring for early signs: less warm air, short cycles, new noise — these are often the first signs of a minor problem that becomes major if you wait.

At AirGreen , our approach is simple: diagnose accurately, correct properly, then validate performance with measurements — so that the repair holds, and not just to "start the machine up again".