A sudden breakdown at the start of the season: AirGreen expertise at work
When a Lennox central heat pump system suddenly stops working as temperatures rise, the situation can quickly become uncomfortable for the whole family.
This is exactly what happened in Boisbriand , on the North Shore of Montreal , where our AirGreen team was called for a total failure of the outdoor condenser .
The customer, concerned about an unusual noise and a complete shutdown of his system, contacted us after noticing that his house was no longer cooling, despite the thermostat being set to 21°C.
Initial inspection: a quick and methodical diagnosis
Upon arrival, we performed a complete inspection of the Lennox outdoor condenser .
Some immediate observations:
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The condenser fan was no longer spinning.
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No compressor vibration.
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The Monark wall breaker (visible next to the unit) appeared intact.
We used our Fluke multimeter to confirm the presence of voltage at the disconnect box: a stable 240 volts. This eliminated any possibility of a power failure.
The rest of the diagnosis focused on the start capacitor , an essential component for starting the fan motor and the compressor.
Step 1: Test the Start Capacitor
After opening the side panel of the condenser, we accessed the dual capacitor (45/5 µF) .
Using a capacitance meter , we measured an effective capacitance of 23 µF on the main circuit , which is about 50% of the nominal value .
Such a weakened capacitor prevents the motor from starting properly and can cause the system to shut down completely.
We therefore replaced the part with a new genuine Lennox capacitor , meeting the same electrical specifications and CSA standard for the Canadian market.
Step 2: Additional inspection and preventive maintenance
During the restart, our team took advantage of the intervention to carry out a deep cleaning of the ventilation fins and the Scroll compressor , often clogged by dust and leaves accumulated at the base.
We also have:
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Tightened the main electrical connections.
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Checked the R-410A refrigerant charge , which was found to be compliant at 145 psi at shutdown.
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Tested contactor continuity and fan motor resistance .
These checks allowed us to confirm that only the capacitor was at fault and that no other components showed any damage.
Step 3: Recommissioning and Performance Validation
Once the part was replaced, we restarted the central heat pump.
In less than a minute, the outdoor fan resumed normal operation, followed by the compressor.
The measurements carried out showed:
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Indoor blown air temperature: 11.7°C.
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Temperature difference before/after: 9°C.
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Stabilized power consumption: 13.2 A.
These data confirmed optimal energy efficiency and a fully restored system.
A satisfied customer and a system ready for summer
The client, relieved, found immediate comfort in his home.
We explained to him the warning signs of a capacitor at the end of its life , including:
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Humming noises without compressor starting.
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A fan that remains motionless despite the current being present.
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Unexpected system shutdowns during cycles.
We also suggested a complete annual maintenance in the spring , including checking all electrical components, to prevent summer breakdowns .
AirGreen expertise on the North Shore
At AirGreen , we emphasize a rigorous and transparent approach to every HVAC system repair :
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CMMTQ certified technicians and RBQ license holders.
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Genuine parts from Lennox, Trane, Goodman, Gree, Midea , and other major brands.
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Fast and documented interventions , with complete digital monitoring for each client.
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Complete coverage of the North Shore , including Boisbriand, Rosemère, Sainte-Thérèse and Terrebonne.
Our mission: to offer durable and safe repairs , without compromising on quality or energy performance.
AirGreen Tips: Avoid Capacitor Failure
To reduce the risk of start capacitor failure:
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Clean the condenser fins at least twice a year.
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Keep the area clear (no leaves, grass or debris within 50 cm).
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Do not leave the heat pump inactive for too long during the winter without power.
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Schedule preventative maintenance before the start of each air conditioning season.
These simple precautions help extend the life of the system and ensure optimal operation throughout the year .
Conclusion: performance restored, confidence assured
Thanks to targeted intervention and precise diagnosis, AirGreen enabled this central Lennox system to regain full performance in less than an hour.
Each repair is an opportunity for us to demonstrate our expertise in HVAC , while guaranteeing the customer professional, fast and lasting service.