Repair of a Tosot wall-mounted heat pump in Rosemont–La Petite-Patrie (Montreal)

In a typical Rosemont–La Petite-Patrie apartment, wall-mounted heat pumps are often installed in high-traffic areas (hallways, above doorways, interior stairwells) to maximize air distribution between rooms. This is precisely the case here: a Tosot indoor unit (active display at 22°C) installed above a door in a relatively narrow space, where airflow and condensation management must be impeccable to avoid any unpleasant surprises.

At AirGreen , we frequently work on this type of installation because an "over a door" configuration is practical... but also more demanding: limited access, drain slope to respect, risk of micro-vibrations, and above all a faster accumulation of dust (air currents + constant passage).

Machine type: Tosot wall-mounted heat pump

The format and location clearly indicate a wall-mounted heat pump (mini-split/wall unit) . Since the brand is provided manually, we are dealing here with a Tosot , a very common brand in residential settings and appreciated for its performance and ease of maintenance when properly cared for.

Model (consistent with the brand)

Without a legible label in the photo, the exact model cannot be confirmed. In this residential setting and with this indoor unit size, we are typically looking at a Tosot Lomo (new generation) or equivalent model. For repair, the important thing is not the exact series name, but the method: a complete diagnosis, a lasting fix, and then validation of the parameters.

The reported symptoms (very common case)

During this type of call, the most common signs are:

• Occasional water droplets/leaks (often after several hours of air conditioning)

• Reduced airflow or a feeling that "it's no longer pushing"

• Damp smell at startup

• Unstable temperature (the machine reaches 22°C, but the comfort level does not follow in adjacent rooms)

In a corridor, these symptoms appear even faster, because the unit is working “against” a less homogeneous volume of air and a return of air that is sometimes disturbed (doors opening/closing, dead zones, etc.).

Our AirGreen assessment: quick, methodical, measured

For a Tosot wall-mounted unit installed above a door, we follow a clear protocol:

1. Airflow control

   • Filter check

   • Checking for fouling of the evaporator (fins) and the turbine (blower)

2. Condensation control

   • Condensate tray inspection

   • Drain flow test (slope, siphon, partial obstruction, micro-blockage)

3. Refrigeration control (if necessary)

   • Measurement of supply/return temperatures (ΔT)

   • Validation of stability in air conditioning/heating mode

   • Observation of behavior (cycles, defrosting, noise, vibrations)

4. Electrical control and sensors

   • Connections, temperature probes, sensor cleanliness

   • Shutter settings and display/control stability

The repair: what we did, in concrete terms

In this type of case (and particularly with a unit placed in a passageway), the long-term solution almost always involves refurbishing the "air + drainage" section :

• Complete cleaning of filters and unclogging of critical areas

• Thorough cleaning of the evaporator (fins) to restore heat exchange

• Cleaning the turbine (where the odor and reduced flow rate often originate)

• Condensate line unclogging

  • controlled purging and restoration of stable flow

  • checking the slope and stagnation points

• Light sanitization (odor control suitable for HVAC) to eliminate bacteria linked to residual moisture

• Final tests

  • stability at 22°C, airflow restored to normal

  • Visual inspection of the drain during prolonged operation

  • validation of comfort in the rooms served

Prominent installation details observed (and why it matters)

• Unit above a door , in a narrow space: the air must be directed and the damper properly calibrated to avoid stagnation areas.

• Height close to the ceiling : if maintenance is not done, dust accumulates faster and efficiency drops.

• High-traffic area : more particles (textiles, dust, micro-debris) → preventive maintenance is even more profitable.

• Active display : the machine is running, but this is not proof of efficiency. A Tosot can "maintain the setpoint" while consuming more energy if the heat exchanger is clogged.

Result: restored comfort, stabilized performance, customer confidence

After the procedure:

• No more leaks and stable condensate flow

• Significantly improved airflow

• More uniform temperature in the service area

• Less noise (the turbine is under less strain)

• Improved efficiency : the machine reaches the setpoint faster, with cleaner cycles

That's exactly what we aim for at AirGreen: not just "repair", but make the Tosot heat pump more reliable , more comfortable, and more economical to use.

AirGreen tips to prevent the problem from recurring

• Clean the filters every 4–6 weeks during periods of intensive use.

• Perform a complete maintenance (including turbine + drain) at least once a year.

• If the unit is in a corridor, avoid leaving obstacles (coats, high storage units) that disrupt the return of air.

• Watch for the first signs: damp smell, weaker breath, or different noise = intervene before the leak.