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”.
Symptoms reported by the client (and confirmed on site)
The owner described it to us:
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The desired temperature is difficult to reach, especially in the afternoon.
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Longer cycles than before (the machine works “non-stop”)
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Unequal comfort levels between the living room and the adjacent area
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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.
Our AirGreen diagnostic approach (methodical, without assumptions)
We always proceed in a logical order, because on a mural, a “small” problem can mask another.
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Complete visual inspection
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Condition of filters, flap, evaporator
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Traces of moisture or overflow in the condensate tray
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Abnormal noises (turbine, engine, vibration)
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Airflow check
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Air outlet measurement, fan stability
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Fouling control (turbine and blades)
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Performance metrics
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Supply/return air temperature (delta T)
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Behavior in cooling and dehumidification modes
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Refrigeration control unit on the outside
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Operating pressures/temperatures
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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:
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reduce the airflow,
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decrease cooling capacity,
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lengthen the cycles,
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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:
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persistent humidity in the unit,
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smells,
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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.
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
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Thorough filter cleaning
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Cleaning of the heat exchanger (evaporator) and air passage areas
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Inspection/cleaning around the condensate tray
Step 2 — Drainage Restoration
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Controlled unblocking and flushing of the condensate line
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Actual flow test (not just “it looks okay”)
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Verification that the unit is no longer retaining moisture unnecessarily
Step 3 — Correction and inspection of the refrigeration connection side
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Correction of the connection in question
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Durability testing and checks to prevent the problem from recurring
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Functional validation (pressures, temperatures, stability)
Step 4 — Final tests under real-world conditions
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Measurement of delta T after stabilization
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Checking the air conditioning and dehumidification modes
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Noise, vibration and regulation control
Result: restored comfort and stabilized performance
After the intervention, the Zephyr wall-mounted heat pump was restored to:
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a colder and more consistent airflow in air conditioning
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improved dehumidification (drier air, faster comfort),
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more normal cycles (less overwork),
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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.
Why this type of repair is common in condos (and how to avoid it)
Condos (downtown, modern towers) often offer:
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Fine dust + cooking (suspended grease),
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prolonged operation in air conditioning mode during the summer.
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humidity builds up if drainage slows down.
Our simple recommendations:
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cleaning the filters at the correct frequencies
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annual preventative inspection (especially before summer),
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rapid intervention as soon as performance drops (the longer you wait, the more fouling and moisture build up).