A performance problem detected on an outdoor unit
On a rainy morning in Sainte-Dorothée, Laval , our AirGreen team received a call from a customer concerned about their Fujitsu wall-mounted heat pump . Installed on a small balcony, the outdoor unit appeared to be working, but the indoor heating had been insufficient for several days. With the still-cool spring temperatures, the customer feared a complete breakdown.
First inspection: a clean but quiet unit
Upon arrival, we found that the outdoor compressor would not start , even though the indoor unit was operating normally. No startup noise, no whirring, just the outdoor fan standing still. The installation, securely mounted on a solid wall bracket, showed regular maintenance: no debris, no obstructions, and intact wiring.
However, one detail caught our attention: slight traces of corrosion on the terminal of the start relay . This oxidation, caused by ambient humidity, could interrupt the electrical contact necessary to start the compressor.
In-depth diagnosis: checking electrical components
Our technicians carried out a series of precise checks:
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Compressor input voltage test – correct power supply.
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Start capacitor inspection – abnormal values detected (capacitance measured at 3 μF for a specification of 6 μF).
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Relay check and terminal cleaning – moisture traces confirmed.
The verdict: A faulty start capacitor , combined with slight oxidation on the relay. This problem prevents the compressor from starting, reducing the unit's heating and cooling capacity.
On-site intervention: capacitor replacement and relay cleaning
We immediately replaced the capacitor with an original Fujitsu part from our mobile stock. After this operation, the relay contacts were thoroughly cleaned with an anti-corrosion product.
Once the heat pump is powered back up:
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The compressor started normally after 10 seconds.
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The outdoor fan resumed its smooth rotation.
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An indoor blowing temperature of 29°C was measured in heating mode, confirming full recovery of performance.
The importance of protecting electrical components from external elements
This case illustrates a common problem in balcony or terrace installations: direct exposure to moisture, especially during periods of rain or frost. Even a well-maintained unit can suffer water infiltration, affecting sensitive electrical components.
At AirGreen, we recommend:
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Adding a lightweight protective roof over the compressor.
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A preventative electrical cleaning before winter.
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Check the capacitor every 2 years, especially on models over 5 years old.
Comfort restored and customer satisfied
A few minutes after restarting, the customer was able to notice a complete return of thermal comfort . Warm air was circulating again in all rooms, and the unit's power consumption had returned to normal.
Before leaving, our technician carried out a complete check of the condensation drain and the electronic parameters of the main board to ensure optimal operation.
AirGreen Expertise: a rapid, sustainable and transparent intervention
This intervention in Sainte-Dorothée demonstrates our commitment to accurately diagnosing each fault before replacing a part. Thanks to our expertise on Fujitsu , Gree , Midea , Daikin and Sharp systems, we offer lasting repairs throughout Greater Montreal, Laval, the North Shore and the South Shore .
We believe that proper maintenance and prompt response to early signs of failure can significantly extend the life of wall-mounted heat pumps and maintain their energy efficiency.