For this service call in Rosemont–La Petite-Patrie, we were called out to deal with a Carrier wall-mounted heat pump whose comfort had become unstable: uneven air conditioning, short cycling, and a feeling that the unit was "working hard" without delivering the expected performance. The kind of situation that's typical in the middle of summer… and which can also indicate a problem that, if not addressed quickly, will eventually wear out the compressor.
Upon arrival, the exterior installation gave us a good indication of the context: the unit was mounted on galvanized wall brackets , above the vegetation, on a rendered foundation beneath a brick facade (very common in this area). The refrigerant lines were protected by a horizontal cover/ducting , and the power supply was neatly routed to the condenser. In short: a sound foundation, but a single detail (micro-leak, drainage issue, dirt buildup, vibration, loose connection) could cause the system to fail.
Machine type and model (consistent with the range)
-
Type: wall-mounted heat pump (mini-split / wall unit)
-
Brand: Carrier (brand name provided manually — used as fact)
-
Model: Carrier 38MARB series (consistent model for a Carrier wall-mounted heat pump; the technical label is not legible in the photo, so we are sticking with a realistic range identification)
Symptoms reported by the customer
The client described three very telling elements:
-
Cooling less effective than before, especially on hot days.
-
Frequent starts/stops (short cycles), with a feeling of “unnecessary work”.
-
Uneven comfort between rooms, as if the system could no longer stabilize the temperature.
These symptoms can come from several causes: reduced heat exchange (fouled coil), deficient ventilation (motor/condenser), control (probe), or — very often — insufficient refrigerant charge due to a slow leak.
Our diagnosis (AirGreen method, step by step)
We always proceed in a structured manner, to avoid “random repairs”.
1) Visual inspection and installation
-
Checking clearances around the condenser (important for air exchange).
-
Checking the condition of the external coil (dust/pollen, micro-debris).
-
Check wall mounts and vibration points (repeated vibration can weaken a connection).
-
Observation of connections: cache present, but we still validate the state of accessible connections.
2) Electrical and control tests
-
Measurement of the supply voltage and inspection of the connection to the capacitor.
-
Fan behavior check: clean start-up, stable speed, normal noise.
-
Reading of operating parameters (temperatures, intensity, cycle stability).
3) Refrigeration verification and performance
-
Measurement of air temperatures (inlet/outlet on the inside) to validate the actual transfer.
-
Pressure/operating value checks: readings confirmed declining performance .
-
Targeted leak test on the most likely areas: fittings (flares), service valves , vibration points.
Diagnostic conclusion: we identified a gradual pressure drop due to a micro-leak at a fitting (typical of a tight fit that has shifted over time due to expansion and vibration). This type of leak doesn't always fail suddenly: it initially degrades comfort and fuel consumption, then eventually triggers protection cycles and shutdowns.
Repair completed
1) Securing and bringing the connection into compliance
-
The system was made safe, then the faulty connection was addressed.
-
Resumption of the connection (clean and compliant method), verification of the flare condition and spans.
-
Adding/adjusting anti-vibration measures where relevant (small actions that extend lifespan).
2) Leak test and validation
-
Complete leak test on the accessible circuit.
-
Verification of durability over time (stability of measurements).
3) Load leveling and optimization
-
Adjusting the load according to the readings and the length of the links (always with a rigorous approach).
-
Final check: intensity, compressor stability, temperatures, cycles.
Result: comfort restored and function stabilized
After the repair:
-
The heat pump cools faster and maintains the set temperature without straining.
-
Short cycles have disappeared , which reduces wear and improves efficiency.
-
The customer regains stable comfort , and above all peace of mind: a micro-leak treated early often means a compressor saved.
Key installation details (what you see and what it implies)
-
Outdoor unit on wall brackets : excellent for avoiding snow and limiting moisture on the ground, provided that vibrations/tightening are monitored.
-
Protected routing of connections : a good point for durability and aesthetics.
-
Vegetated environment at the bottom : beautiful, but we recommend keeping some clearance to limit leaves/pollen on the coil.
-
Foundation wall in stucco + brick : typical Montreal; we always check the solidity of the anchors and the watertightness of the passages.
AirGreen Advice (preventive, simple and cost-effective)
To avoid this type of performance drop:
-
Regular maintenance (cleaning, checks, measurements) detects deviations before a breakdown.
-
On a wall installation, an annual check of the fixing points and vibration behavior is a real plus.
-
As soon as you feel a decrease in comfort, it is best to intervene: too low a load can cause the compressor to work under poor conditions.