A service call for a heat pump that was no longer heating
At AirGreen , our technicians regularly work on Fujitsu wall-mounted heat pumps in the greater Montreal area. On this day, our team was called to Boisbriand , on the North Shore , to diagnose a Fujitsu wall-mounted heat pump installed on the side wall of a newer home. The customer had noticed that their system was no longer producing hot air, even though the compressor seemed to be operating normally.
Installation context
The outdoor unit, installed about one meter above the ground on a galvanized wall bracket, served a main living area via a 12,000 BTU Fujitsu indoor wall unit. This configuration is typical of modern single-family homes: a compact, efficient, and quiet installation , perfectly suited to forced-air air conditioning and heating.
The problem reported by the customer—a lack of heat in winter—is a common symptom that can have several causes: refrigerant leak, clogged coils, faulty defrost sensor , or even a stuck reversing valve .
Complete diagnosis by the AirGreen team
Upon our arrival, our technician performed a visual inspection of the outdoor unit. There were no signs of oil leaks or excessive icing. However, a repetitive clicking noise during startup immediately caught our attention.
After connecting our digital manifold and taking pressure readings, we found that the system was displaying too low a discharge pressure in heating mode, indicating a partial restriction in the refrigeration circuit . Such a restriction prevents the R-410A refrigerant from circulating properly between the evaporator and condenser.
The cause: a reversing valve stuck in the intermediate position
Electrical analysis then revealed that the reversing valve's control coil wasn't receiving the full 24V signal needed to switch it. By manually manipulating the valve, our technician confirmed that it was getting stuck in the partial position, causing a loss of efficiency and preventing the heating mode from engaging.
So we have:
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Turn off the power supply.
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Disconnected and cleaned the reversing valve coil .
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Checked the wiring and replaced a oxidized connection in the outdoor control box.
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Applied a dielectric lubricant to prevent future corrosion.
Once the system was restored, the valve operated normally. Operating pressures returned to normal ranges: approximately 360 psi discharge and 125 psi suction at an outside temperature of 3°C.
Results: a high-performance and quiet Fujitsu heat pump
After a full 15-minute cycle, the indoor blown air temperature increased from 18°C to 34°C , confirming that the heating was fully restored. The customer, who was considering a complete replacement, was pleasantly surprised to discover that a targeted repair was enough to extend the life of his unit by several years.
Preventive maintenance recommended by AirGreen
To avoid this type of problem recurring, we have advised:
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Annual cleaning of the coils with a non-corrosive product.
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Checking the condensate drain to prevent water accumulation in the sump.
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A complete electrical inspection every fall before the heating season.
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Automatic defrosting manually tested at each maintenance.
These simple steps can help prevent reversing valve failures, often caused by abnormal cycling or residue buildup on the connectors.
The AirGreen difference on the North Shore
Working on HVAC systems like this requires extensive knowledge of Fujitsu electronics and refrigeration components . At AirGreen, we continuously train our technicians on the latest generation of wall-mounted and MultiZone heat pumps, whether they use R-410A or R-32 , to provide fast and accurate diagnostics.
Whether you are in Boisbriand , Terrebonne , Sainte-Thérèse or Blainville , our team provides fast, transparent and guaranteed HVAC repairs , using original manufacturer parts. We work for both individuals and small residential buildings, always with the same rigor.
In summary: comfort restored and savings made
Thanks to a targeted repair and precise diagnosis, the Fujitsu wall-mounted heat pump in Boisbriand is now working like new. The customer once again benefits from stable, energy-efficient, and quiet heating , without having to invest in a costly replacement.
It is this methodical and honest approach that has made AirGreen's reputation across Montreal, Laval, Longueuil, the North Shore and the South Shore : a trusted HVAC service, where each intervention aims for performance and durability.
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