In a condo in Ville-Marie , the client contacted us about a problem that quickly became frustrating: the Fujitsu wall-mounted heat pump was sometimes blowing lukewarm air, sometimes cold, and the indoor temperature fluctuated throughout the day. The system was working, but no longer providing the expected comfort —exactly the kind of situation where a thorough diagnosis makes all the difference.
The photo shows a wall-mounted indoor unit installed high up , near the ceiling, in a modern space (smooth walls, sharp angles, understated finish). This type of placement is common in condos: it promotes good air circulation, but it also requires impeccable installation and maintenance (condensate drainage, air circulation, airtight refrigerant connections, etc.).
The system in question: Fujitsu wall-mounted heat pump (mini-split)
This is clearly a wall-mounted heat pump (mini-split) : a compact indoor unit, a blower flap, and refrigerant lines running to the outdoor unit (not visible in the photo). Since the exact model isn't legible, we're using a model consistent with recent residential installations from the brand: Fujitsu Orion XLTH (R-32) — a line popular in Quebec for its stable heating performance and its ability to maintain comfort when temperatures drop.
Reported symptoms: unstable heating and decreased efficiency
The client described three typical symptoms:
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Irregular heating (temperature that struggles to stabilize)
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Longer response time than before (the room heats up slowly)
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Frequent cycling (more frequent starts/stops, feeling of "forcing" the engine)
In a condo, these problems have an immediate impact: discomfort, disturbed sleep, and sometimes even reduced productivity when working remotely.
Our AirGreen approach: a complete, step-by-step diagnosis
At AirGreen, we avoid assumptions. A heat pump can "work" while losing efficiency. So we proceeded as follows.
1) Quick and logical checks (without unnecessary disassembly)
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Visual inspection of the indoor unit (condition of the casing, fins, flap, sensors)
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Checking air circulation and filters
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Control of settings (modes, settings, fan speed, programming)
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Observation of behavior during actual operation (stabilization, noise, oscillation)
Result: nothing alarming on the filter/fan side, but a clear impression of reduced thermal capacity , which led us to suspect a refrigeration problem or deeper internal fouling.
2) Technical measurements: temperatures, pressures and cycle consistency
Next, we took specific measures:
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Blower temperature vs. ambient temperature
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Stability of the heating cycle
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Defrosting check (frequency, duration, consistency)
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Reading the parameters and validating the protections
These indicators often point to a common cause in residential settings: insufficient refrigerant charge (often due to a micro-leak or a fitting that has shifted slightly over time).
3) Leak detection: the real cause
We conducted a methodical leak search on the critical points:
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Fittings (flares/flanges) at the ends of the lines
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Accessible sections of the links
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Vibration points and areas of potential friction
Confirmed diagnosis: micro-leak at a fitting , small enough not to "empty" the system quickly, but sufficient to degrade efficiency and cause unstable heating.
Repair completed: resealing + performance restoration
Once the cause was found, we applied a complete repair (not a temporary “patch”).
Repair steps
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Securing the intervention
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Correction of the faulty connection (reworking and tightening to the appropriate torque)
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Leak test and stability check
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Vacuuming according to best practices (removal of moisture and air)
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Adjusting the refrigerant charge according to system specifications
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Final heating test (stabilization, blowing temperature, cycle behavior)
Why this method is important
A wall-mounted heat pump is unforgiving of errors: a slight leak or incorrect charging can lead to:
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performance decline
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too frequent defrosting,
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higher consumption
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Premature compressor wear.
Result: restored comfort and renewed confidence
After the procedure:
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The heat pump has regained a stable airflow temperature.
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The heating became constant and fast
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The cycles have become more regular (fewer unnecessary stops/starts)
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The customer immediately noticed a feeling of comfort "like before," with a quieter and more consistent system.
And most importantly: the customer leaves with the certainty that the repair addresses the real cause , not just the symptom.
This case reminds us of something we often see in Montreal.
In urban areas like Ville-Marie , there are many condo developments and the requests often revolve around:
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performance decreases “without outright failure”,
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uneven heating from one room to another,
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discomfort despite the machine appearing to be running normally.
Very often, the triggering element is subtle (micro-leak, slight pressure loss, connection, or insufficient maintenance), but the impact on comfort is major.
Is your Fujitsu wall-mounted heat pump showing similar signs?
If your Fujitsu wall-mounted heat pump is heating less effectively, blowing lukewarm air, or becoming unstable, we can intervene with the same approach: precise diagnosis, lasting repair, and comprehensive testing . At AirGreen, our goal is simple: to restore comfort, optimize performance, and prevent future problems.