Performance loss in the heat: complete diagnosis of a failing Bora system
During this service call in Laval, our AirGreen team was tasked with servicing a Bora wall-mounted air conditioner whose outdoor unit showed obvious signs of weakness. Installed directly on a concrete slab, in close proximity to the exterior wall and the electrical disconnect panel, this residential HVAC system had been in place for several years and had served well… until its performance noticeably declined.
The customer reported a specific problem: the indoor unit was blowing air, but the cooling was insufficient, especially on hot days. At times, the device seemed to operate normally, then suddenly lost efficiency, leaving the room at an uncomfortable temperature. This type of intermittent symptom requires a rigorous and methodical approach.
Description of the Bora system and installed configuration
The equipment in question was a Bora wall-mounted mini-split air conditioner, consisting of a wall-mounted indoor unit (not visible here) and a compact outdoor condenser. This type of system is very common in Montreal, Laval, Longueuil, as well as on the North Shore and South Shore, due to its ease of installation and efficiency for residential cooling.
Based on the observed dimensions and configuration, the system capacity was likely around 12,000 BTU, ideal for a main room or a small apartment. The outdoor compressor, although compact, plays a critical role: it must efficiently reject the heat captured inside to maintain a stable cooling cycle.
Visually, several elements caught our attention during the initial inspection:
- Outdoor unit placed directly on the ground without an elevated support.
- Proximity to the wall slightly limiting air circulation.
- Visible refrigerant lines with partially worn external insulation.
- Electrical disconnect box properly installed but exposed to the elements.
- Fan grille clean on the surface but requiring internal inspection.
Observed technical symptoms
After turning on the system, we confirmed the customer's observations:
- Irregular start-up of the outdoor fan.
- Buzzing noise at the moment of cold call.
- Air conditioning cycle that starts then stops prematurely.
- Indoor air barely cooled despite a low thermostat setting.
- More unstable operation as the outside temperature increased.
These symptoms clearly indicated a problem on the outdoor condenser side, probably related to an electrical component or a startup failure.
In-depth HVAC diagnosis: a disguised electrical failure
At AirGreen, every intervention is based on concrete measurements, never on assumptions. So we proceeded step by step.
Electrical power supply check
We started by securing the installation via the disconnect box, then measured the input voltage. Result: stable 240V supply, with no drop or anomaly. So the problem was not from the electrical panel.
Inspection of internal components
By opening the Bora condenser panel, we identified several critical elements:
- A slightly worn contactor, with signs of oxidation.
- Electrical connections exposed to moisture.
- And especially, a weakened run capacitor, measured outside its normal range.
The capacitor plays a crucial role: it provides the necessary impulse to start the compressor and the fan. When it fails, the motor may hesitate, hum, or not start at all.
In this specific case, the capacitor was no longer delivering enough capacity, which explained:
- Random startups.
- The outdoor fan was not always running.
- The compressor was stopping due to thermal protection.
Refrigeration system check
Once the electrical problem was identified, we proceeded with a check of the refrigeration circuit:
- Pressures measured within normal ranges.
- No visible signs of leakage.
- Low indoor blowing temperature before repair, then improved after service.
This confirmed that the refrigerant was not the issue, avoiding an unnecessary recharge intervention.
A targeted repair that restored the performance of the Bora air conditioner
Service performed by AirGreen
Our goal was not just to "get the device running again," but to restore its optimal operation. Here are the steps taken:
- Replacement of the faulty capacitor with a compatible part.
- Cleaning of electrical connections.
- Checking the contactor and tightening the terminals.
- Cleaning of the outdoor coil to improve heat exchange.
- Complete test of the outdoor fan.
- Controlled system restart.
- Performance measurement after repair.
From the moment it was restarted, the change was obvious: the outdoor fan started instantly, without abnormal noise, and the compressor maintained a stable cycle.
Result: comfort restored and system stabilized
After repair:
- The air blown inside was noticeably cooler.
- The room temperature dropped quickly.
- No premature shutdown observed.
- Silent and consistent operation.
The customer immediately felt the difference. This type of targeted repair often prevents a complete system replacement, especially when the compressor is still in good condition.
Why this type of failure is common
In many interventions in Laval, Montreal, and on the North Shore, we find that capacitors are among the first components to weaken in a wall air conditioner.
The main causes:
- Exposure to external heat.
- Repeated start cycles.
- Natural aging of electronic components.
- Humidity and temperature variations.
A capacitor can gradually lose its capacity without completely failing, making diagnosis more subtle.
Mistakes to avoid with a Bora wall air conditioner
Ignoring signs of weakness
A device that cools less effectively or makes noise should not be ignored. Waiting can worsen the situation and damage other components.
Forcing the system continuously
Letting an air conditioner run despite difficult starts can cause compressor overheating, which is much more expensive to repair.
Neglecting exterior maintenance
The condenser coil must remain clean. Dirt buildup reduces efficiency and increases the system's internal pressure.
Why choose AirGreen for your HVAC repairs
At AirGreen, we operate daily in Montreal, Laval, Longueuil, on the North Shore and the South Shore to diagnose and repair residential HVAC systems. Each call is handled precisely, taking into account the specifics of the equipment and its environment.
Our approach is based on:
- A rigorous technical diagnosis.
- Transparency in interventions.
- Targeted and durable repairs.
- In-depth knowledge of brands like Bora.
In this case in Laval, a simple part replaced at the right time prevented a major breakdown and extended the system's lifespan.