Sharp wall-mounted heat pump repair in Ville-Marie (Montreal): a quick return to comfort, without compromise

In a condo in Ville-Marie , we were contacted about a Sharp wall-mounted heat pump that was no longer delivering the expected performance: uneven heating, a feeling of drafts, and a performance that dropped, especially in the morning and late afternoon. On site, the installation was typical of an urban dwelling: a Sharp wall-mounted indoor unit installed high up in a hallway/bedroom, tight access, and intervention using a ladder and a full set of service tools—a context where precision is key, because you can't just "test randomly."

In this type of situation, our objective is simple: diagnose quickly, repair properly, and stabilize the system to avoid a recall .

What we observed upon arrival

The unit in question was a Sharp wall-mounted heat pump , very consistent with a residential “mini-split” setup (indoor wall unit + outdoor unit). Since the exact model wasn't visible in the photo, we treated the installation as a recent Sharp model , typically from the Sharp ZU1 (R-32) family, frequently installed in 12,000 to 18,000 BTU units in condominiums.

Symptoms reported by the occupant:

• Heating that is “present then absent”, especially in cycles

• Uneven comfort: warm room but lacking stability

• Starts correctly, then performance drops

• Slight unusual noise during operation (intermittent)

Our diagnostic method (and why it avoids unpleasant surprises)

At AirGreen, we follow a logical sequence, because a wall-mounted heat pump can “appear” to be broken when the problem is sometimes peripheral (drainage, airflow, sensors, power supply, etc.).

1) Checking airflow and heat exchange

We always start with what immediately influences performance:

• Filter and airflow condition

• Condition of the heat exchanger (coil): fine dust, oily film, partial obstruction

• Measurement of the temperature difference (inlet/outlet) in heating mode

Result: correct airflow, but underperforming heat exchange at times — which points to a transfer issue (dirt, sensors, or refrigerant).

2) Drainage and condensation tray control

Even with heating, a drainage/condensation problem can cause:

• Intermittent stops

• Noises (gurgling, vibration)

• Internal humidity and disrupted sensors

We found a partially obstructed drain (very common in condos: dust, micro-debris, biofilm). It wasn't "completely blocked," but enough to create unstable conditions.

3) Refrigeration system check: pressure, superheat/subcooling and leak detection

When a machine heats up intermittently, we must confirm that the refrigeration circuit is stable:

• Operating measures

• Inspection of fittings (flanges), traces of oil, possible micro-leaks

• Targeted leak testing of critical points

Result: we identified a slight looseness on a fitting (not a big leak, but enough to disrupt the charge and cause the efficiency to drop on some cycles).

The repairs carried out (clean, complete, durable)

1) Unblocking and securing the drainage

• Cleaning the bin and clearing the drain

• Controlled rinsing and flow test

• Verification that the slope and the exit are functional

Purpose: to eliminate shutdowns and instability related to internal humidity.

2) Restoration of the heat transfer system (technical cleaning)

• Targeted cleaning of the indoor unit's heat exchanger

• Dust removal from critical areas (without “flooding” the electronics)

• Validation of the airflow and the blower valve

Goal: to restore efficient heat exchange, especially in heating.

3) Connection correction + complete refrigeration procedure

For a reliable intervention, we don't just "tighten and leave." We have:

• Corrected the connection in question (set to the appropriate torque)

• Secured the seal

• Performed a complete service procedure (including charge control and stabilization), adapted to the R-32 refrigerant used in recent Sharp models.

• Functional testing in cycles, then stability validation

Result: stable comfort and restored performance

After the procedure:

• More consistent heating, cleaner cycles

• The perceived temperature in the room is more stable.

• Reduction of intermittent noise (related to unstable conditions + drainage)

• Customer reassured: system restarted with consistent parameters and normal performance

In a condo like the one in Ville-Marie, a wall-mounted heat pump needs to be predictable : you want comfort without wondering if the system will fail on the next cycle. That's exactly what this repair has restored.

Why this type of failure occurs (and how to avoid it)

The three most frequent causes seen on murals in urban areas:

1. Drainage partially obstructed (dust + humidity + biofilm)

2. Fine fouling of the heat exchanger , even if the filters seem “not so bad”

3. Micro-leaks or connections that move slightly with vibrations and thermal cycles

Our simple recommendation:

• Regular maintenance (especially in condos)

• Periodic technical cleaning

• Proactive check before winter when the machine is under heavy use