A Mitsubishi outdoor unit losing efficiency: a typical early summer service call
At AirGreen , we were recently called to Boucherville , on the South Shore of Montreal , for a Mitsubishi Electric wall-mounted heat pump that was showing signs of failure. The customer contacted us after noticing that the unit was running non-stop, but without effectively cooling the house.
When we arrived, the outdoor compressor—a Mitsubishi Electric Hyper Heat (Zuba) model—was emitting a slight humming noise, but the temperature inside the home remained stable at around 24°C, despite the set temperature being set at 20°C.
Diagnosis: Thorough inspection of the HVAC system
Our technicians first carried out a complete analysis of the refrigeration circuit . The first step was a visual inspection of the outdoor unit, installed on a raised aluminum base, against a brick wall typical of South Shore residences.
Here are the main findings:
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No excessive vibration or abnormal noise from the compressor.
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Low operating pressures , suggesting partial loss of refrigerant.
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Refrigeration duct insulation damaged by wear and exposure to the weather.
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Condensate drain slightly clogged, which had caused water to accumulate around the indoor unit.
To confirm the hypothesis of a leak, our technician used an electronic leak detector and located a micro-leak at the level of a weld of the flare connection .
Intervention: sealing, insulation and complete recharging of the system
Once the leak was identified, our team took the following steps:
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Recovery of the refrigerant remaining in the circuit to avoid any release into the environment.
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Complete repair of the fitting at the base of the compressor, with a new flare and replacement of the seal.
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Vacuum the system for 45 minutes to remove all traces of moisture.
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Recharge with R-410A refrigerant , in accordance with Mitsubishi Electric specifications.
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Complete replacement of the exterior refrigeration insulation , with high-density UV-resistant insulation.
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Performance test : after restart, the temperature delta measured between suction and blowing reached 9.2°C — proof of optimal performance restored.
Result: restored comfort and optimized energy efficiency
After our intervention, the Mitsubishi Electric heat pump returned to full efficiency. The customer immediately noticed that the indoor temperature dropped more quickly and that the compressor's operating cycle had returned to normal.
We have also recommended some simple preventative measures to extend the life of the device:
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Clean the internal filters every month during the warm season.
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Visually inspect exterior ducts each spring for signs of wear or rodents.
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Schedule an annual inspection with AirGreen to check gas load and drain condition.
What this repair demonstrates
This service call perfectly illustrates the difference between a simple check and professional AirGreen maintenance .
Our approach is always based on:
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A precise and documented diagnosis , carried out with professional instruments;
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A careful intervention , respecting environmental standards;
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A post-intervention performance check to validate the stability of the system.
At AirGreen , we understand that every heat pump breakdown can become a real inconvenience. That's why we respond quickly throughout Montreal, Laval, Longueuil, the North Shore and the South Shore , to offer a reliable, transparent and sustainable HVAC repair service.
Why choose AirGreen for your Mitsubishi Electric repairs?
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Mitsubishi Electric certified technicians trained in Hyper Heat technologies.
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Fast and local service , covering all of Greater Montreal.
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Advanced diagnostic tools (thermal cameras, leak detectors, pressure analyzers).
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Full warranty on all repairs carried out.
Your Mitsubishi heat pump deserves maintenance that matches its performance. With AirGreen, you benefit from recognized expertise and trusted service that extends the life of your equipment.