Winter roof repair for a broken Fujitsu heat pump
At AirGreen , we provide reliable HVAC service throughout the year, even in Montreal 's harshest winter conditions. This service call, conducted in the Côte-des-Neiges–Notre-Dame-de-Grâce neighborhood, involved a Fujitsu wall-mounted heat pump installed on a flat roof covered in snow and ice. The client, a rental property owner, contacted us after noticing that the heat pump had stopped producing heat for several days, despite the outdoor unit apparently being operational.
The context of the intervention
In the middle of January, temperatures were around -15°C , and the outage caused rapid cooling of the homes served by the system. The outdoor unit, mounted on a raised metal support to avoid direct contact with snow, appeared intact at first glance. However, the presence of a thick layer of ice around the base and on the supply pipes suggested a defrosting problem.
Detailed diagnosis of the fault
Upon arrival, our technician undertook a complete inspection of the refrigeration circuit . Pressure tests revealed low pressure inconsistent with the ambient temperature, suggesting a partial obstruction in the circuit or an iced sensor . We then conducted an analysis of the defrost cycle using the integrated electronic control module.
The main findings:
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Defective defrost sensor (thermistor) , no longer detecting the outside temperature correctly.
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Ice buildup on the exchanger , drastically reducing performance.
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Frozen water drainage , preventing condensation from draining from previous cycles.
These combined anomalies triggered an automatic safety shutdown of the compressor.
Steps of repair
After disconnecting the power supply, we undertook a series of specific actions:
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Complete manual defrosting of the unit with hot air and industrial defroster, without damaging the condenser fins.
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Replacement for the original Fujitsu defrost sensor , recalibrated to the exact model parameters.
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Complete cleaning of the electrical box and connections , which showed traces of humidity.
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Thawing and clearing the drain , then adding an antifreeze heating cable to prevent any recurrence.
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Complete test of the defrost cycle and measurement of operating pressures after restart.
Checks and results
After reactivating the system, the heat pump began a complete automated defrost cycle , followed by a return to heating mode with optimal performance:
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Blown air temperature: 33°C at the indoor outlet.
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Operating pressure restored to 125 psi (low) and 380 psi (high) .
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Responsive and quiet defrost cycle.
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No error detected on the electronic card.
Thanks to this repair, the thermal performance was completely restored , and the owner was able to regain stable heat in all the dwellings served.
AirGreen Tips for Winter
Heat pumps installed on flat roofs are particularly vulnerable to winter conditions. To prevent breakdowns:
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Clean the base of the unit regularly to prevent snow and ice buildup.
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Check defrost sensors every fall before frost.
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Install a heating cable to keep the condensation drain free.
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Schedule annual preventative maintenance with AirGreen to calibrate the system before winter.
AirGreen expertise in Montreal
This intervention in Côte-des-Neiges–Notre-Dame-de-Grâce demonstrates AirGreen's ability to operate in the most challenging conditions. Our certified technicians have advanced expertise on Fujitsu systems, as well as on all major brands such as Midea, Gree, Sharp, Trane, Lennox, Goodman and Zephyr .
We operate throughout Greater Montreal — Montreal, Laval, Longueuil, the North Shore and the South Shore — to guarantee optimal comfort and sustainable energy performance for our residential and commercial customers.
Conclusion
Thanks to a quick and methodical intervention, AirGreen enabled this Fujitsu heat pump to fully resume its service, even in freezing cold. At AirGreen, each repair is an opportunity to demonstrate our commitment to quality, durability and the comfort of Montrealers .