Repair of a Carrier wall-mounted heat pump in Rosemont–La Petite-Patrie (Montreal)

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:

1. Cooling less effective than before, especially on hot days.

2. Frequent starts/stops (short cycles), with a feeling of “unnecessary work”.

3. 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.