Exceptional Repair of a Mitsubishi Mr. Slim Mini Split Heat Pump in Plateau-Mont-Royal
Discover how AirGreen expertly revived an aging Mitsubishi Mr. Slim heat pump, extending its life and restoring peak performance for a satisfied customer in Montreal.
Take a tour of the installation
Each number is a point we check on site. Switch between summer and winter to watch air and heat move.
In summer, the outdoor unit rejects the house's heat outside.
Generic illustration of this type of installation, not a survey of this job site. Tap a number.
Mounted level on a wall plate, high enough for the air to reach the whole room, with enough space around it to slide the filters out easily.
The refrigerant lines, the communication cable and the drain go through the wall in a single opening, sealed against water, cold air and insects.
Two insulated copper pipes connect the two units. Outside, a line cover can protect them from sun, knocks and weather.
A shut-off switch near the outdoor unit isolates it safely for service. It must stay accessible at all times.
The compressor and the fan. In heating mode it captures heat from the outdoor air, even in winter, and moves it inside.
On the ground or on the wall, it keeps the unit above accumulated snow. The unit stays clear and defrost water can drain away.
The fan needs to blow freely. Storage, a fence or a wall too close, and efficiency drops while noise goes up.
Revitalizing a Trusted System: Bringing New Life to a Mitsubishi Mr. Slim in Montreal
In the heart of Montreal’s vibrant Plateau-Mont-Royal neighborhood, we recently had the opportunity to work on a beloved Mitsubishi Mr. Slim mini-split heat pump. This trusted unit, which had served our client through many seasons, was beginning to show signs of wear. Rather than replacing it outright, our customer wanted to explore the possibility of extending its lifespan. Thanks to our team’s expertise and dedication to preserving quality, we were able to bring this machine back to peak performance, much to our customer’s delight.
The Machine: Mitsubishi Mr. Slim Mini Split Heat Pump
The Mitsubishi Mr. Slim is a reliable mini-split heat pump known for its efficiency and durability. Designed to handle the extreme temperatures of Montreal’s seasonal swings, this system provides both heating and cooling in an energy-efficient manner. Many homeowners in Montreal, Laval, and beyond choose Mr. Slim for its reputation of consistent performance, compact design, and relatively low maintenance needs. However, like any mechanical system, it requires periodic servicing to continue functioning at its best.
Our team understands the engineering behind Mr. Slim units, and we approach each service call with the goal of optimizing the equipment rather than just providing a quick fix. This dedication to quality is part of what sets us apart and keeps our clients coming back for regular maintenance and repairs.
Inspection and Diagnosis: Identifying Key Issues
Our first step upon arrival was a thorough inspection of the unit. As an HVAC team with a deep understanding of Mitsubishi systems, we knew to look for specific issues that can arise in aging units. Some common problems in older Mr. Slim models include:
- Clogged Filters and Coils: Over time, dirt and debris can accumulate, reducing efficiency and causing the system to work harder.
- Refrigerant Leaks: This is a common issue in older systems, which can drastically reduce the unit’s cooling capacity.
- Worn-Out Compressor: The compressor is the heart of any heat pump, and its performance can decline with age.
In this case, we discovered a combination of clogged filters, which restricted airflow, and a slight refrigerant leak. Both issues were contributing to the unit’s reduced efficiency and the noticeable lack of cooling power our customer had been experiencing. Additionally, the unit’s outdoor coil was partially obstructed by dust and dirt, which further limited its ability to regulate temperature effectively.
Repair Process: Meticulous Attention to Detail
After diagnosing the issues, we got to work. Our team is known for its attention to detail and commitment to delivering quality repairs. Here’s how we approached the restoration of this Mr. Slim heat pump:
1. Cleaning and De-clogging the Filters
First, we carefully removed and cleaned the filters. Over time, filters in mini-split systems can accumulate dust, pollen, and other airborne particles, especially in urban areas like Plateau-Mont-Royal. By restoring the filters to pristine condition, we ensured that airflow would be unobstructed, allowing the unit to operate more efficiently.
2. Fixing the Refrigerant Leak
A refrigerant leak can severely impair a heat pump’s ability to cool a space. For this repair, we used specialized tools to detect the exact location of the leak. After locating it, we repaired the leak and added the appropriate amount of refrigerant to restore the system’s cooling capacity. This process requires precision, as the wrong amount of refrigerant can lead to inefficiency or even damage the compressor.
3. Outdoor Coil Cleaning and Maintenance
The outdoor coil was carefully cleaned to remove any dirt buildup. This step is crucial because a dirty coil reduces heat transfer, making the system work harder than necessary. After cleaning, we applied a coil protectant to help prevent future buildup and extend the unit’s longevity.
4. Comprehensive System Testing
Once the repairs were complete, we conducted a thorough testing procedure to ensure the unit was running at peak efficiency. We checked the system’s cooling performance, verified that the refrigerant levels were correct, and ensured that the airflow was unobstructed. This final testing phase is essential in our repair process, as it confirms that everything is functioning optimally and that our client’s expectations are met.
The Outcome: A Happy Customer and a Refreshed Heat Pump
Our client was thrilled with the results. By extending the life of their Mitsubishi Mr. Slim, we provided a cost-effective solution that avoided the need for a full replacement. Not only did the unit’s performance improve, but it also offered peace of mind to our client, knowing that their reliable heating and cooling system was back in top form and ready for Montreal’s demanding climate.
Why Choose AirGreen for Your HVAC Needs?
At AirGreen, we pride ourselves on our expertise in HVAC repair and our commitment to customer satisfaction. Here’s why clients in Montreal, Laval, Longueuil, Rive Nord, and Rive Sud trust us:
- Experienced Technicians: Our team has years of experience working with a wide variety of HVAC systems, including Mitsubishi heat pumps.
- Quality Repairs: We focus on delivering repairs that last, helping you get the most out of your HVAC investment.
- Customer-Centric Approach: We listen to our clients’ needs and tailor our services to meet their specific requirements.
- Preventive Maintenance: In addition to repairs, we offer maintenance services that can help extend the life of your equipment.
The Importance of Regular Maintenance
One of the key lessons from this service call is the importance of regular maintenance. HVAC systems, like the Mitsubishi Mr. Slim, are designed to last for many years, but only if they are properly cared for. Regular cleaning, inspections, and timely repairs can prevent small issues from becoming costly problems down the line.
Benefits of Regular HVAC Maintenance
- Improved Efficiency: Regular maintenance ensures that your system operates at peak efficiency, which can lower your energy bills.
- Extended Lifespan: Taking care of your equipment can add years to its life, delaying the need for costly replacements.
- Better Air Quality: Clean filters and coils mean better indoor air quality, which is especially important for households with allergy sufferers.
- Peace of Mind: Knowing that your system is well-maintained gives you peace of mind, especially during Montreal’s hot summers and cold winters.
Conclusion: A Job Well Done
This repair in Plateau-Mont-Royal is a perfect example of how dedicated service and expertise can breathe new life into an older HVAC system. At AirGreen, we believe that every service call is an opportunity to prove our commitment to excellence. By taking the time to carefully diagnose issues and perform meticulous repairs, we give our customers the confidence that their HVAC systems are in the best possible hands.
For anyone in Montreal, Laval, Longueuil, Rive Nord, or Rive Sud considering HVAC repairs or maintenance, we invite you to contact AirGreen. Whether you need a quick repair or a full maintenance check, our team is ready to help you stay comfortable, whatever the season.
The big day, step by step
The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.
The symptoms, since when, the model (on the unit's label) and the error code if there is one.
We look for the cause, not just the symptom: readings, components, installation.
Repair, part to order or replacement, depending on the failure. We explain what we found.
The repair is done and parts replaced as needed.
The unit is restarted and checked in its operating modes.
What caused the failure and what can keep it from coming back.
- Your callThe symptoms, since when, the model (on the unit's label) and the error code if there is one.
- On-site diagnosisWe look for the cause, not just the symptom: readings, components, installation.
- The optionsRepair, part to order or replacement, depending on the failure. We explain what we found.
- The workThe repair is done and parts replaced as needed.
- TestsThe unit is restarted and checked in its operating modes.
- AdviceWhat caused the failure and what can keep it from coming back.
Your own project, step by step
What to do, season by season
Three habits per season for this unit. They take a few minutes and prevent many calls.
- Clean the indoor unit's filters.
- Clear leaves and debris left on the outdoor unit by winter.
- Test cooling before the first hot days.
- Clean the filters more often when the unit runs a lot.
- Keep plants away from the outdoor unit.
- Check that no water drips from the indoor unit.
- Rake the leaves around the outdoor unit.
- Test heating before the first cold days.
- Book periodic maintenance before winter.
- Keep snow away from the stand and the front of the unit.
- Let the unit defrost: it is normal.
- Never hit the ice on the fins; call us if the unit stays iced up.
Four statements: true or false?
It all comes down to details you have just seen.
1. In heating mode, the outdoor unit can produce water.
During defrost cycles. That water must drain away without forming ice.
2. You pick the capacity with a simple square-footage rule.
Windows, insulation, orientation and how the room is used all count. Capacity is chosen on site.
3. A multi-zone connects several indoor heads to a single condenser.
One head per room, all on the same condenser. Each room keeps its own temperature.
4. The disconnect can sit behind the patio furniture.
It must stay accessible: it is what shuts the unit off for service.
0 / 4 right answers
What people ask us about this kind of work
What should I have ready before calling?
Repair or replace?
Does a wall-mounted heat pump heat in winter?
Wall-mounted or multi-zone: how do I choose?
Where does the outdoor unit go?
Are there grants?
Do I need a permit?
Does AirGreen hold the required licences?
Is the estimate free?
No question matches. Write to us: we answer.
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Text and photo: a real AirGreen Climatisation & Chauffage job. The diagrams are generic illustrations of the type of installation, not a survey of this job site. Sources of the added figures: airgreen.ca product pages (NEEP / AHRI performance), Hydro-Québec (Heat pumps page, LogisVert, read on 13 October 2026), Régie de l’énergie (rate D as of 1 April 2026).