Behind the scenes of an emergency wall-mounted heat pump repair during Laval’s worst storm (true story)

When expertise meets responsiveness: a critical AirGreen intervention in Laval

At AirGreen, we know that wall-mounted heat pump breakdowns never happen at the right time — especially during the harshest weather. This article recounts a real emergency repair in Laval, right in the middle of a winter storm, where our team combined speed, technical precision, and commitment to restore comfort for a family caught off guard by a sudden failure.

Let’s look back at a high-stakes HVAC repair carried out in extreme conditions — and the key takeaways for any homeowner.

The context: a historic snowstorm and a brutal system failure

It was January, in Laval’s Sainte-Rose district, with the region facing record lows of -27°C, violent winds, and heavy snow. A family of four, including an infant, suddenly lost all heat when their 18,000 BTU Fujitsu wall-mounted heat pump shut down overnight. No heat, no indoor unit response.

The client, understandably distressed, called us at 6:18 a.m. Thanks to our emergency management system, a technician team was already on its way by 7:05 a.m..

On-site diagnosis: internal short circuit and failed defrosting

Upon arrival, we observed several things:

• The outdoor unit was covered in a thick layer of frost, jamming the fan blades.

• The compressor was frozen solid, likely due to a poorly executed defrost cycle in the days before.

• The indoor control panel wasn’t receiving any signal — we detected a short circuit on the main board using a multimeter test.

The heat pump was in total shutdown, unable to initiate a cycle, and further compressor damage was likely if power wasn’t cut.

Immediate repair thanks to our mobile stock system

At AirGreen, every emergency vehicle is stocked with parts compatible with the most common brands, including Fujitsu, Gree, Sharp, Midea, and Lennox. Fortunately, we had on hand:

• A replacement control board compatible with the Fujitsu KZAH series

• A defrost heating element suited to this model

• Anti-freeze lubricant for fans

Steps performed on site:

1. Shut down main power supply

2. Removed the damaged main board

3. Installed the new board and reprogrammed the Inverter protocol

4. Manually defrosted the outdoor unit using indirect hot air

5. Tested all temperature sensors to confirm functionality

Total intervention time: 2 hours and 15 minutes, including extended heating mode tests.

Immediate result: restored heat, zero secondary damage

By 9:45 a.m., the wall-mounted heat pump was back on. The warm airflow was stable and quiet, and the outdoor unit resumed cyclic, balanced operation. The system was also reconfigured with a customized defrost sequence tailored to Laval’s extreme weather conditions.

“Thanks to you, our baby was able to sleep warm that night. I’ll never forget how quickly and calmly you fixed everything.” – Client, Sainte-Rose (Laval)

Why heat pumps fail during extreme cold

Improper initial configuration

• Defrost cycles spaced too far apart by factory settings

• Humidity sensor poorly positioned on the outdoor unit

• Insufficient tilt during installation, causing frozen water to pool

Lack of preventive maintenance

• Clogged indoor filters for several months

• Blocked drainage, leading to frost buildup

• No electrical check-up before the heating season

At AirGreen, we always emphasize the importance of professional HVAC maintenance before winter, especially for units installed in high-exposure areas like Laval, the North Shore, or Longueuil.

Best practices to avoid system failure

For homeowners:

• Schedule a complete fall maintenance

• Make sure outdoor unit clearance complies with guidelines

• Watch for abnormal frost signs (loud fan noise, reduced heat)

For installers:

• Always adjust defrost settings based on local conditions

• Test drainage under simulated weather conditions

• Protect electrical connections with winter-grade sleeves

AirGreen: fast and lasting HVAC solutions in emergencies

Our advantage:

• 24/7 availability during winter

• Service vehicles stocked with certified parts for all major brands

• Trained technicians skilled in quick diagnostics under extreme weather

Our top-priority service zones:

• Laval (Sainte-Rose, Chomedey, Vimont)

• North Shore (Boisbriand, Terrebonne, Sainte-Thérèse)

• South Shore (Longueuil, Boucherville, Saint-Hubert)

• And of course, all of Montreal

We don’t just fix problems — we prevent future failures with personalized technical follow-ups and precise recommendations for every installation.