When winter hits hard in Québec, the reliability of heating and air conditioning systems becomes essential. In Bois-des-Filions, a customer recently contacted AirGreen about an issue affecting a Mitsubishi wall-mounted heat pump installed beneath an outdoor deck. A common situation, but one that required precise expertise, thorough technical evaluation, and a safe repair despite environmental constraints.
An Exposed System and Harsh Winter Conditions
The outdoor unit of this Mitsubishi MUZ-D heat pump was mounted on a wall bracket directly beneath a wooden deck. While this installation may initially appear to provide some protection from precipitation, it also comes with several challenges, especially during the winter season:
-
Build-up of ice and melting snow close to the compressor, which can affect water drainage and cause backflow issues.
-
Restricted ventilation due to the limited space between the unit and the deck.
-
Risk of thermal shock to the casing, caused by alternating freeze/thaw cycles from water dripping down from above.
The customer had noticed a heating malfunction, along with a strange noise at startup. Additionally, the unit seemed to freeze over faster than usual. A service call was clearly needed.
Full Inspection by Our AirGreen Technicians
Upon arrival in Bois-des-Filions, our certified technicians performed a full system inspection. Here’s what we found:
-
Partial blockage of condensation drainage due to ice build-up.
-
Poorly insulated refrigerant lines, exposing the piping to moisture and freezing temperatures.
-
Slight compressor vibration, amplified by the wall-mounted installation on a cracked concrete surface.
-
The outdoor disconnect box was in poor condition, with visible water infiltration inside.
These details, although minor individually, were significantly compromising the heat pump’s performance in frigid weather.
Repairs Performed On-Site
After explaining the situation to the client, we carried out a series of targeted repairs, all in compliance with electrical and HVAC safety codes:
-
Manual defrosting of the outdoor unit using a controlled hot air system.
-
Replacement of the outdoor disconnect box with a weatherproof unit rated for extreme conditions.
-
Complete re-insulation of the refrigerant lines using high-density thermal tape and a waterproof outer wrap.
-
Verification of the R-410A refrigerant charge, which remained within tolerance levels, ruling out any leaks.
-
Adjustment of the wall mounting brackets and installation of anti-vibration pads to eliminate the humming noise.
-
Application of anti-corrosion coating to metal fasteners exposed to moisture.
Thanks to these repairs, we restored the full heating performance of the system while also improving its durability for future winters.
Why This Type of Installation Requires Special Attention
Wall-mounted heat pumps like this Mitsubishi MUZ-D are often considered ideal for small homes or units with limited access. However, when installed beneath balconies or decks, they present several invisible risks:
-
Upward discharge of hot air, reducing efficiency.
-
Blocked condensation drainage during thaw cycles.
-
Limited accessibility for emergency maintenance.
At AirGreen, we train our teams to anticipate these challenges and propose customized solutions, whether during installation or a repair visit.
The Customer’s Satisfaction in Bois-des-Filions
The client particularly appreciated our transparency, our quick response, and the care we took with every detail. They also expressed relief at having avoided a complete breakdown in the middle of the cold season. Thanks to our repairs, their Mitsubishi heat pump can now run smoothly without interruption, all while maintaining optimal energy efficiency.
Practical Advice for Installations Under a Balcony
For all our clients in Bois-des-Filions, Laval, Montréal, or elsewhere on the North Shore, here are a few tips if your outdoor unit is installed beneath a structure:
-
Check regularly for melting snow or ice buildup near the unit.
-
Clear fallen leaves and debris that may block the grilles.
-
Have the line insulation inspected annually.
-
Install a deflector or protective shield to divert melting water away from the unit.
By following these simple actions, you can prevent costly breakdowns.
AirGreen’s Commitment to Long-Term Service
At AirGreen, we don’t just repair — we prevent. Every service call is an opportunity to optimize your HVAC systems, offer sound advice, and extend the lifespan of your equipment.
Our service calls in Bois-des-Filions, Longueuil, the South Shore, and beyond reflect our hands-on expertise and our commitment to getting the job done right.