When expertise, patience, and precision make all the difference in a challenging HVAC service call
In the world of residential HVAC, some service calls require more than just technical skills—they demand advanced diagnostics, a methodical approach, and the ability to fix hidden problems left behind by other contractors. That’s exactly what we encountered during a complex wall-mounted heat pump repair in Laval, in a single-family home built in the early 2000s. This case study highlights the technical challenges we overcame, the detailed steps of our intervention, and the added value AirGreen brings to this type of situation.
The starting point: a heat pump blowing lukewarm air… in the middle of winter
The client contacted us in January, concerned about a 12,000 BTU Fujitsu wall-mounted heat pump installed a few years earlier by an independent contractor. Despite outdoor temperatures hovering around -5 °C, the indoor unit could no longer properly heat the main living area. The client had noticed a gradual drop in performance, along with unusual noises at startup.
Technical evaluation: a series of small errors with major consequences
Right from our first visit, we identified several issues:
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The outdoor unit was tilted backwards, causing poor condensate drainage and frost buildup on the coil fins.
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The electrical connection wasn’t sealed against moisture, with visible signs of corrosion.
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No nitrogen pressure test had ever been performed on the refrigerant lines, suggesting a slow leak in the system.
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The initial vacuum was insufficient, with residual moisture detected during our vacuum gauge test.
Combined, these issues had caused a progressive loss of efficiency, premature compressor wear, and excessive energy consumption with little to no heat output.
Action plan: disassemble, diagnose, restore
Given the complexity of the situation, our team followed a three-step protocol:
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Full nitrogen analysis and pressure test
We injected dry nitrogen into the system to pinpoint a leak at a poorly tightened flare fitting, located behind the indoor unit. It was in a very tight, hard-to-reach space that had been badly bent during the original installation. -
Partial replacement of the refrigerant lines
Instead of replacing the entire line set, we replaced only the damaged copper section, avoiding invasive and costly demolition work. -
Extended vacuum pull and refrigerant recharge
After purging all residual moisture, we performed a 45-minute deep vacuum, followed by a full recharge of R-410A, measured to the exact gram according to Fujitsu specifications. -
Re-leveling the outdoor unit and upgrading electrical protection
We repositioned the outdoor unit on new anti-vibration mounts, added a new sealed electrical junction box, and used thermally insulated fittings for long-term protection.
Results: restored performance, reduced consumption
As soon as the system was turned back on, the difference was clear. The heat pump was delivering 38 °C air at the vent, with a stable and consistent indoor temperature curve. The client noticed an immediate drop in energy usage, along with a return to the level of comfort they had originally expected.
Practical takeaways from this service call
This case reveals many common mistakes we see regularly. Here are the key lessons every homeowner should keep in mind:
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A poorly installed heat pump might not fail right away, but its lifespan and efficiency will be significantly reduced.
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A proper vacuum pull is non-negotiable to ensure a durable installation.
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Refrigerant line connections must be perfect—even a slightly loose flare fitting can compromise the entire system.
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A post-installation inspection is essential, even if the unit seems to work normally at first.
Why trust AirGreen for your HVAC repairs?
At AirGreen, we don’t just repair—we analyze, validate, and optimize every component of your system. Our technicians are trained to work on all major brands, with in-depth expertise in Fujitsu, Gree, Lennox, Midea, and several other popular units installed throughout Montréal, Laval, Longueuil, the North Shore, and the South Shore.
Our goal is not just to get your unit running again—it’s to guarantee stable, long-term, energy-efficient performance, in full compliance with Québec’s strictest HVAC standards.
Proven expertise, beyond just repairs
This Laval case is just one example among hundreds. Each year, we’re called in to:
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Diagnose unexplained drops in system performance.
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Restore installations damaged by frost or humidity.
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Repair heat pumps where the original install didn’t meet required standards.
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Optimize aging systems to boost efficiency.
In every case, we deliver a customized solution, with transparency, precision, and professionalism.