When temperatures suddenly drop in Montréal, Laval or on the North Shore, a failing wall-mounted heat pump becomes a major problem. The natural reflex is to want to replace the unit as quickly as possible, sometimes even the same day. But acting in a rush, without preparation or professional guidance, can lead to costly mistakes, affect your comfort, and even compromise your building’s integrity.
At AirGreen, we’ve been called in to handle dozens of winter emergency situations over the years. Thanks to our on-the-ground expertise, we’ve identified 6 critical mistakes you must absolutely avoid when replacing a wall-mounted heat pump in the middle of winter.
1. Ignoring the correct sizing of the new heat pump
One mistake we see far too often: replacing an existing unit with a poorly sized model, simply because it’s in stock. In Saint-Jérôme, we recently had to uninstall a 24,000 BTU heat pump that was oversized for a 950 sq. ft. condo. The result? It ran in short cycles, causing premature wear, temperature instability, and increased electricity bills.
🔧 AirGreen Tip: Never choose a heat pump based on guesses. A complete heat load calculation is mandatory, even in an emergency.
2. Trying to reuse old piping or existing electrical cables
In winter, when time is tight, some installers reuse the old lines from the previous unit. Serious mistake. The diameters may not match the new technical specs, the lines could be clogged or oxidized, and the R-32 refrigerant used in newer models is incompatible with certain older materials.
💡 Example: in Brossard, a client tried to do a self-install using old lines — we had to remove everything, clean, vacuum the system, replace the wiring, and start from scratch.
3. Choosing a model that’s not built for Québec’s winter climate
Some wall-mounted units simply aren’t designed to maintain performance at -25°C or -30°C. Installing a low-end reversible air conditioner and assuming it will perform like a high-efficiency heat pump is a potentially dangerous mistake.
🔎 In Laval, a client had installed a non-Energy Star certified unit. After three days of deep freeze, the unit froze solid, and the condensed water damaged the outer wall.
Our recommendations:
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Gree Extreme, Fujitsu KZAH, or Sharp ZU1: all suited for Québec winters.
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Look for HSPF ratings ≥ 10 and SEER ratings ≥ 18.
4. Overlooking safe winter installation procedures
Installing a heat pump when it’s -15°C or colder requires specific procedures:
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Protect the outdoor unit from snow.
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Use heated insulation sleeves for the piping.
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Ensure the outdoor workspace is safe and clear.
📍 During an emergency installation in Longueuil, our team had to manually shovel a frozen balcony, install a reinforced wall bracket with thermal insulation membrane, and add a compact lift pump to prevent freezing or clogging.
5. Failing to check for available grants (LogisVert, RénoClimat, etc.)
Even in an emergency, it’s essential to verify what incentives are available. A Fujitsu KZAH 12,000 BTU heat pump we installed in Sainte-Thérèse qualified our client for a $1,704 LogisVert grant. She had no idea until we called her!
✔️ With smart replacement, you can:
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Get up to 50% of the costs covered.
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Improve your home’s energy rating and resale value.
6. Hiring a company without winter intervention experience
Installing a wall-mounted heat pump in January is nothing like a summer installation. Technicians must know how to work in extreme conditions, understand defrost procedures, adjust charge pressures according to outdoor temperature, and comply with CSA winter safety standards.
🎯 At AirGreen, we use specialized equipment like high-speed recovery stations that operate under -20°C, and our technicians are RBQ and TEQ certified, with specific training for this type of work.
Field Case: Emergency Call in Montréal-Nord
Last February, a client called us in a panic: his 9-year-old heat pump suddenly stopped working at -22°C, and his home was becoming unlivable. In under 48 hours, we:
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Assessed the site.
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Defrosted the old unit and secured the power supply.
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Installed a MIDEA25 9,000 BTU R-32 unit, with brand new piping, a compact lift pump, certified breaker.
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Provided all the documents for his $1,820 LogisVert grant.
Result: a customer saved from the deep freeze, and a bill cut in half.
Conclusion: Act fast, but smart
Replacing a wall-mounted heat pump in winter is never something to improvise. It requires expertise, speed, and a customized approach. At AirGreen, we know that every hour counts. But that should never come at the expense of quality, safety, or your long-term comfort.
Dealing with a heating or wall-mounted cooling emergency in Montréal, Laval or on the South Shore? Call on our dedicated team — fast, trained, and committed to quality work.