Repair of a Zephyr wall-mounted heat pump in Ville-Marie (Montreal): performance restored, comfort stabilized

In a condo in Ville-Marie , our AirGreen team was called in to service a Zephyr wall-mounted heat pump ( mini-split type indoor wall unit). At first glance, the unit seemed to be working (active display), but comfort was no longer guaranteed: uneven cooling , a feeling of lukewarm air at times, and performance that was no longer keeping up during peak periods.

As is often the case in condo environments, the objective was twofold: to repair effectively , but also to ensure stability (silence, dehumidification, constant temperature), without a temporary “patch”.

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Symptoms reported by the client (and confirmed on site)

The owner described it to us:

• The desired temperature is difficult to reach, especially in the afternoon.

• Longer cycles than before (the machine works “non-stop”)

• Unequal comfort levels between the living room and the adjacent area

• Slight musty smell intermittently (a common indicator of drainage/evaporation)

On a Zephyr wall unit , these symptoms can stem from several causes: restricted airflow , heat exchanger fouling , a partially blocked drain , or insufficient refrigerant charge (micro-leak, flare fitting, etc.). Don't guess: measure.

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Our AirGreen diagnostic approach (methodical, without assumptions)

We always proceed in a logical order, because on a mural, a “small” problem can mask another.

1. Complete visual inspection

   • Condition of filters, flap, evaporator

   • Traces of moisture or overflow in the condensate tray

   • Abnormal noises (turbine, engine, vibration)

2. Airflow check

   • Air outlet measurement, fan stability

   • Fouling control (turbine and blades)

3. Performance metrics

   • Supply/return air temperature (delta T)

   • Behavior in cooling and dehumidification modes

4. Refrigeration control unit on the outside

   • Operating pressures/temperatures

   • Checking connections, insulation, and indicators of micro-leaks

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What we found (the “real” problem)

In this particular case, there were two combined causes — typical of breakdowns that drag on:

1) Air restriction and degraded heat exchange

The filters and the heat exchanger were sufficiently fouled to:

• reduce the airflow,

• decrease cooling capacity,

• lengthen the cycles,

• and increase residual moisture (odors).

2) Partially obstructed drainage (condensation not properly drained)

The drain wasn't completely blocked, but it was slowing down the drainage , which promotes:

• persistent humidity in the unit,

• smells,

• risk of overflow (droplets / runoff).

In addition, our measurements showed a slight anomaly in the refrigeration system's operation . While not a complete breakdown, it was significant enough to warrant further investigation: we therefore inspected the fittings and confirmed that a flare fitting required correction (sealing/tightening), followed by an integrity check of the circuit.

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Work carried out: repair + complete upgrade

At AirGreen, we prefer a “clean” intervention that restores the machine to its true level, rather than a simple restart.

Step 1 — Technical cleaning of the indoor unit

• Thorough filter cleaning

• Cleaning of the heat exchanger (evaporator) and air passage areas

• Inspection/cleaning around the condensate tray

Step 2 — Drainage Restoration

• Controlled unblocking and flushing of the condensate line

• Actual flow test (not just “it looks okay”)

• Verification that the unit is no longer retaining moisture unnecessarily

Step 3 — Correction and inspection of the refrigeration connection side

• Correction of the connection in question

• Durability testing and checks to prevent the problem from recurring

• Functional validation (pressures, temperatures, stability)

Step 4 — Final tests under real-world conditions

• Measurement of delta T after stabilization

• Checking the air conditioning and dehumidification modes

• Noise, vibration and regulation control

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Result: restored comfort and stabilized performance

After the intervention, the Zephyr wall-mounted heat pump was restored to:

• a colder and more consistent airflow in air conditioning

• improved dehumidification (drier air, faster comfort),

• more normal cycles (less overwork),

• and above all, a temperature stability typical of a healthy inverter wall unit.

The customer immediately noticed the difference: the room cooled down faster, without feeling warm air, and the unit became discreet again — exactly what you want in a condo in Ville-Marie.

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Why this type of repair is common in condos (and how to avoid it)

Condos (downtown, modern towers) often offer:

• Fine dust + cooking (suspended grease),

• prolonged operation in air conditioning mode during the summer.

• humidity builds up if drainage slows down.

Our simple recommendations:

• cleaning the filters at the correct frequencies

• annual preventative inspection (especially before summer),

• rapid intervention as soon as performance drops (the longer you wait, the more fouling and moisture build up).