A silent compressor and a worried customer: a precise and reassuring AirGreen diagnosis
On a beautiful May morning, our AirGreen team was called to Sainte-Dorothée , in Laval , to work on a North Cool wall-mounted heat pump installed on the exterior wall of a single-family home. The customer had noticed for several days that the unit was no longer blowing cold air, even though all the indicator lights seemed to indicate normal operation.
First observation on the ground
The outdoor compressor, securely mounted on a wall bracket, appeared clean and well-maintained. However, upon starting the system, we noticed an abnormally quiet compressor , while the fan spun freely. No pressurizing noise, no sign of vibration—a classic indicator of an internal electrical problem .
Before any manipulation, we have:
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Turn off the power at the dedicated circuit breaker,
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Inspected the power relay wiring,
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Tested the supply voltage to the compressor and fan (230V confirmed).
Complete diagnosis: the invisible breakdown
Using our digital multimeter and a capacitance meter, we quickly identified the problem: the compressor's start capacitor had completely lost its rated capacitance. The label indicated 40 µF, but the actual measurement reached only 4.7 µF. This drastic drop prevented the compressor from starting, without generating any obvious error codes on the control board.
We also checked:
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Compressor winding continuity (no break detected),
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Internal resistance of the motor (stable values),
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No visible refrigerant leaks around the flare fittings.
The AirGreen solution
We replaced the defective capacitor with a certified capacitor of the same value and high thermal tolerance . Before closing the unit, we cleaned the condenser fins using a non-corrosive product and blew out the electrical compartment with dry compressed air.
After powering up, the compressor started immediately , generating stable pressure and a discharge temperature within specifications. The indoor air dropped from 24°C to 18°C in less than 10 minutes , a clear sign of restored efficiency.
Final check and recommendations
Once the system was stabilized, we proceeded to:
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A reading of the compressor inrush current (5.6 A, perfectly within the standard),
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A condensation and evaporation test to ensure proper circulation of the refrigerant,
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A check of the condensate drainage of the indoor unit.
The relieved customer could see the difference immediately. We then recommended a complete annual maintenance that included checking the condensers, cleaning the internal filters, and inspecting the refrigerant level.
Why do capacitors often fail?
The capacitor is a crucial component in HVAC systems: it stores the energy needed to start the compressor and fan. On wall-mounted units exposed to the sun , like here in Sainte-Dorothée, excessive heat can cause premature aging of the internal electrolyte . A simple thunderstorm or electrical surge can then finish off the component.
This is why AirGreen recommends:
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Installing an HVAC surge protector (to protect the electronic board),
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A check of the capacitor capacity during each maintenance,
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Preventive replacement after 5 to 7 years of intensive use.
AirGreen Expertise in Laval and Beyond
At AirGreen , we combine technical expertise and professional rigor to ensure the longevity of your North Cool, Midea, Fujitsu, Gree, Zephyr, Trane, and more equipment.
Our interventions cover:
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Laval (Sainte-Dorothée, Chomedey, Fabreville, Vimont, etc.),
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Greater Montreal ,
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The North Shore and the South Shore .
Every service call includes a complete diagnosis , a detailed report , and preventative recommendations to ensure the reliability of your HVAC system throughout the year.
Conclusion
This repair in Sainte-Dorothée demonstrates how a single component can affect an entire air conditioning system. Thanks to a quick and meticulous intervention , our team allowed this North Cool heat pump to regain its full performance.
At AirGreen , we believe that lasting comfort comes from accurate diagnosis , quality repair , and respect for the customer .