Installation of a GREE FreeMatch R32 two-head heat pump in the Pierrefonds-Roxboro borough of Montreal

The outdoor coil: what a homeowner can clean themselves, and what can destroy a unit in ten minutes

All our installation pages repeat the same instruction: clean the outdoor coil once a year. None has yet explained how to do it, or, above all, what must never be done. Yet this is the maintenance task most frequently performed incorrectly in Quebec, and the one that costs the most when it goes wrong, because a damaged coil does not trigger any error code.

The Pierrefonds-Roxboro project was particularly well suited to this. There, we installed a GREE FreeMatch R32 wall-mounted heat pump with 2 heads on a GWHD(30)ND6MO outdoor unit: 18,000 BTU/h in the main living area and 12,000 BTU/h in the second zone, for a total indoor capacity of 30,000 BTU/h. The outdoor unit is installed on a rooftop terrace, on an aluminum stand resting on sleepers—a setup whose design we detailed in our Dollard-des-Ormeaux and Plateau-Mont-Royal articles, and which we will not revisit here. What interests us this time is what happens to this unit after the installers leave.

The project: two zones, one exposed outdoor unit

The house is heated with electricity, with no ductwork. Two zones were selected: the main living area, with an 18,000 BTU/h head, and a second enclosed zone with a 12,000 BTU/h head. The electric baseboards remain in service everywhere else.

The outdoor unit, for its part, lives outside twelve months a year, exposed to rain, snow, pollen, and salt. In the project photo, it is covered in droplets after a shower, which is perfectly normal: a condenser is designed to get wet. What it is not designed for is being submerged in water, breathing through a layer of dust, or being hit with a high-pressure jet.

Why a GWHD(30)ND6MO for only two heads

This is the first time in this series that a two-zone project has received this model, and the reasoning deserves to be explained because it is not based on capacity.

Three lines in the table made the decision:

• The maximum elevation change increases from 15 m to 25 m. The two smallest models in the range, the GWHD(18) and GWHD(24), are limited to 15 m between the outdoor unit and the indoor units. The GWHD(30)ND6MO is the first model in the range to offer 25 m. In a building where the unit is on the roof and the heads are several levels below, this single line can rule out the two smaller models.
• The precharged length increases to 40 m and the maximum total length to 80 m, compared with 30 and 60 m for the 24k. A rooftop layout is structurally longer than a ground-level layout, as we explain in our Dollard-des-Ormeaux article.
• It is the most efficient model in the entire FreeMatch range. This may be surprising, so here are the figures: the GWHD(30)ND6MO has an EER of 4.0 W/W and a COP of 4.19 W/W, the best of the five models, ahead of the 42k (3.81 / 3.9), the 24k (3.8 / 3.9), the 18k (3.52 / 3.9), and the 36k (3.52 / 3.56). Its EER2 of 12.5 is matched only by the 18k. In other words, the most efficient model in the range is neither the smallest nor the largest: it is the one in the middle.

The 30,000 BTU/h of connected indoor heads represent 106% of the nominal cooling capacity (28,400 BTU/h) and exactly 100% of the nominal heating capacity (30,000 BTU/h). The complete reading of the “min. – max.” line, which explains why exceeding the nominal value is not oversizing, can be found in our Dorval article.

What gets dirty is not what you see

Here is the point that almost no one explains, and that completely changes how you clean.

A condenser draws air through its coil from the rear and side faces, then expels it through the front-mounted fan. Everything floating in the air—pollen, seeds, dryer lint, street dust, grass clippings—is therefore carried from the outside into the coil and settles deep between the fins.

Two practical consequences:

1. The visible face is the least dirty. A coil that looks clean from the outside may be clogged throughout its depth. An appliance that “works well but costs more than before” is very often one whose coil is not breathing properly.
2. Rinsing is done in the opposite direction of the airflow, that is, from the inside out whenever access allows. Rinsing from the outside face simply pushes the dirt farther into the coil.

The cost is silent: a fouled coil raises condensing pressure, the compressor runs longer to achieve the same result, consumption increases, and capacity decreases during heat waves. No indicator light comes on. We have written about it in other contexts—orchard pollen in Havelock, field dust in Saint-Télesphore, samaras and resin in Rigaud—but the mechanism is the same everywhere.

What a homeowner can do themselves

Once a year, ideally in spring before the cooling season:

1. Turn off the power at the disconnect switch. Not just the unit with the remote control: the outdoor disconnect switch. The fan must not be able to start while your hands are inside.
2. Remove anything that has accumulated around and beneath the unit. Leaves, samaras, twigs, bags, and patio furniture moved closer during the summer. Clear space all around is not an aesthetic preference; it is a condition for the unit to operate.
3. Rinse with a garden hose at normal pressure, from top to bottom, directing the water against the airflow whenever the configuration allows. Lukewarm water and time are better than force.
4. Check that water drains beneath the unit. Water that pools beneath a condenser in September becomes a sheet of ice in November.
5. Look at the fins. Flattened or bent areas are visible to the naked eye and can be corrected with a fin comb, never with a screwdriver.

That's all. Five actions, about thirty minutes, and most of the benefit is secured.

The actions that destroy a coil in ten minutes

We have observed each of the following on equipment we were called to repair.

• The pressure washer. It is the leading destroyer of coils in Quebec. Aluminum fins are as thin as a sheet of paper; a high-pressure jet flattens them in a single pass. Once flattened, they block the air they were meant to let through, and the loss of capacity is permanent.
• Household cleaners. Kitchen degreasers, oven cleaners, acids, alkaline products: aluminum is not stainless steel. These products attack the metal and the surface treatment on the fins. Only cleaners formulated for coils, with an appropriate pH and diluted according to their instructions, belong here—and in most household situations, water is enough. The case of a chemically aggressive environment, such as a spa installed one metre from the condenser, is covered in our Côte-des-Neiges–Notre-Dame-de-Grâce article.
• Brushing across the fins. A brush should always move in the direction of the fins, never across them. A single crosswise stroke can flatten dozens.
• Directing the spray toward the electrical compartment. The controls side of a condenser is not an area to spray. Protect it or avoid it.
• Straightening the fins with a screwdriver. A fin comb costs a few dollars and follows the fin spacing; a screwdriver tears them. Fins can also be bent accidentally: a tool placed on the cabinet that slips into the coil causes exactly the same damage, as we wrote candidly in our Côte Saint-Luc article.
• The full winter cover. A heat pump operates in winter. We explained this in our Dollard-des-Ormeaux article: a complete tarp traps moisture and prevents the unit from drying out during defrosting.

The surface coating on the fins

The coils of several manufacturers, including GREE, have a protective coating applied at the factory to the fins—that is what gives the coil its bluish tint, clearly visible in the photo of this job. This coating slows corrosion and helps water drain away rather than remain as a film.

The consequence is simple: this coating rubs off and is removed. Abrasive cleaning, a wire brush, or a harsh product removes the protection along with the dirt, and the coil then ages faster than a bare coil that had simply been left alone. That is why we repeat that water and patience beat force and cleaning products.

What gets dirty faster in the west end of the island

Every area has its nuisances. In the west end of the Island of Montreal, where the Pierrefonds-Roxboro borough borders the Rivière des Prairies and contains some of the island’s largest natural areas, three issues come up repeatedly: pollen and tree seeds in spring, dryer lint when a dryer vent is located near the unit, and de-icing salt for units installed near a driveway or sidewalk cleared with salt.

Let’s add a reminder that is particularly relevant to this borough: the floods of 2017 and 2019 hit riverside areas hard. The complete reasoning behind installing a condenser in a flood-risk area—base height established above the known flood elevation, disconnect switch above that line, and what to do, or especially not do, after submersion—is covered in our Ormstown article.

What a yearly maintenance visit actually includes

The second half of this article is for homeowners comparing maintenance contracts who do not know what they are buying. The honest answer: contracts vary enormously, and a low-priced “annual cleaning” sometimes amounts to nothing more than a fifteen-minute rinse.

What is measured and recorded

A thorough visit for a dual-zone system includes at least:

• Electrical readings. Supply voltage, compressor current draw compared with the rated current on the data plate — 13.5 A RLA on this model —, and the condition and tightening of the terminals. A loose terminal heats up, oxidizes, and eventually fails on a sweltering evening.
• The condition of both coils, outdoor and indoor, and the indoor filters of each head.
• The drains, tested until actual water flow occurs, not merely inspected.
• Airflow and louver operation on each head, in both modes when the season permits.
• The history of error codes read directly from the unit: most systems retain a record of anomalies that have never triggered an alarm.
• The condition of the mounting surface, vibration isolators, and line-set insulation — we return to this below.

On an inverter system, some conventional measurements require caution: a temperature difference between return air and supply air is meaningful only if the modulation level at the time of the reading is known, and an infrared thermometer measures a surface, not air. We devoted part of our Sainte-Clotilde article to this subject.

“Filling up the Freon” is not maintenance

This is the most important point in this section, and the one most often misunderstood.

A refrigeration circuit is sealed. It does not consume refrigerant the way an engine consumes oil. A system that is low on refrigerant has a leak, period. Adding a charge without looking for the leak means paying twice: once for the refrigerant, and once for the same service call the following summer, with a compressor that has also been running undercharged in the meantime.

Three practical consequences:

1. Topping up refrigerant is not part of normal annual maintenance. If it is offered to you every year as a routine procedure, ask about the leak.
2. On a multi-split system, the charge must be weighed; it cannot be guessed from the pressure. It depends on the actual length of the lines, as we detailed in our articles on Ahuntsic-Cartierville and Anjou.
3. Handling halocarbons is regulated in Quebec and must be carried out by qualified contractors. A documented leak search, recovery, and recharge are part of the work; a discreet “top-up” is not.

The maintenance report: what a real document contains

A maintenance contract that leaves no written record cannot be verified. The report we provide contains, at a minimum: the date, identification of the unit and both heads with their serial numbers, electrical readings, the observed condition of the coils and filters, drain tests, codes read, corrective actions taken, and above all what was observed but not corrected, along with the associated recommendation.

This last line is what protects the customer. A bent fin noted in 2026 and found to have worsened in 2028 tells a story; the same fin, never mentioned, tells none, and the warranty discussion becomes one person's opinion against another's.

Corrosion: salt, moisture, and dissimilar metals

An outdoor unit operates in a chemically aggressive environment: constant moisture, de-icing salt carried by boots and vehicles, spray, and freeze-thaw cycles.

Three checks at every visit:

• The bottom of the casing and the base pan. This is where water and salt accumulate. A clogged pan retains water instead of draining it.
• Fasteners and the support. An aluminum support, steel screws, and water create a pairing of dissimilar metals; galvanic corrosion develops slowly, precisely where the unit is held in place. Fasteners must be selected for compatibility and inspected; they are not installed once and forgotten.
• The condition of the insulation on exposed lines, whose deterioration from ultraviolet rays is covered in detail in our Dollard-des-Ormeaux article.

The structure beneath the unit ages too

On this job, the unit rests on an aluminum support, with anti-vibration mounts at the contact points, the whole assembly placed on wooden sleepers that distribute the load. The design of this type of installation was covered elsewhere; what falls under maintenance is its aging:

• Level. A condenser must remain level so that water can leave its base pan through the intended openings. A unit that tilts with the seasons retains water on one side, and that water freezes.
• Anti-vibration mounts compress and harden over time; replacing them takes just a few minutes and restores acoustic comfort that has gradually been lost.
• Exposed wood does not last forever. Wood sleepers should be inspected and replaced before they warp beneath the unit.

The schedule we provide to the customer

For a two-zone system, it fits on one page:

• Every 4 to 8 weeks during the intensive season: rinse the filters of both heads.
• In the spring: clean the outdoor coil, clear the surrounding area, and check drain flow before the first heat wave.
• In the fall: run the system in fan-only mode for twenty to thirty minutes after the last cooling use to dry the indoor coil, then clear snow from around the outdoor unit.
• Once a year: the complete technical visit described above, ideally scheduled in May or September rather than during a heat wave, for the reasons explained in our L'Île-Bizard–Sainte-Geneviève article, which also addresses the homeowner's role as the first line of maintenance.

Mistakes to avoid

1. Using a pressure washer on a coil. The damage is immediate and permanent.
2. A household product on treated aluminum.
3. Cleaning without switching off the disconnect.
4. Accepting an annual “Freon top-up” without documented leak detection.
5. Paying for a maintenance contract that produces no written report.
6. Covering the unit for the winter.
7. Allowing patio furniture to move closer to the unit during the summer and never putting it back in place.

Rebates and eligibility

A heat pump installed alongside electric heating may qualify for energy-efficiency programs currently in effect in Quebec, notably Hydro-Québec's LogisVert and Rénoclimat. Chauffez vert targets conversions from oil or propane. Criteria and amounts change: we validate them when the file is opened. The declared AHRI code must match the combination actually installed; otherwise, an application may be rejected for a purely documentary reason. It is also worth noting that a unit with documented maintenance retains evidentiary value when a claim is filed: the absence of a maintenance record is one of the most common reasons for rejection.

Why entrust your system's maintenance to AirGreen

Proper installation is half the job; the other half plays out over twelve years. At AirGreen, we install and maintain HVAC systems in Montreal, Laval, Longueuil, the North Shore, and the South Shore, and our maintenance visits produce a written report that remains in the customer's file: readings, observed condition, corrections, unresolved observations, and dated recommendations.

For a wall-mounted heat pump installation, annual HVAC maintenance, or an assessment of an existing unit in Pierrefonds-Roxboro, the West Island, or elsewhere in Greater Montreal, contact our team: we measure, we document, and we tell you what your unit actually needs—not what would be convenient to sell you.