A service call reveals a leak and poor condensate drainage
At AirGreen , we were recently called to Sainte-Rose, Laval, to work on a Lennox HVAC system showing signs of advanced corrosion and abnormal condensate flow. The customer had been noticing a decrease in the performance of their central heat pump for several weeks, as well as the presence of water around the plenum. This type of symptom is typical of a problem with the evaporator coil or a clogged condensate drain .
Initial diagnosis: corrosion, leakage and water accumulation
Upon opening the service panel, our team noticed fouling of the coil and visible corrosion on the lower sheet metal of the indoor module.
The points observed:
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Presence of stagnant water in the drainage tray.
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Advanced oxidation on the lower left edge of the metal structure.
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Several wires not properly insulated in the electrical compartment.
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Traces of refrigerant leakage around the thermostatic expansion valve (TXV).
These clues pointed our diagnosis towards a combined problem of refrigerant leakage and poor condensate management .
Step 1: Checking the refrigeration circuit
Since the Lennox system has a multi-loop copper coil , we performed a nitrogen pressure test to detect any leaks. Result:
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Slow leak located at the solder of a capillary connection.
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Stable pressure on the rest of the circuit.
After draining the system, repairing the broken joint and resuming the copper-phosphorus brazing, we put the entire circuit back under vacuum and then recharged it according to the manufacturer's specifications.
Step 2: Complete cleaning and restoration of the drainage
Another major problem was the partially blocked condensate drain , causing an overflow into the secondary tank.
We have :
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Unclogged and rinsed the PVC drain line using a biological cleaner.
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Installed a drain elbow to improve the flow slope.
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Applied thermal insulation to the pipe to prevent external condensation.
This step helped prevent any recurrence of water leaks or damage around the plenum.
Step 3: Electrical safety and airflow optimization
During the diagnosis, we also noticed that some control wires were poorly protected and connected with non-waterproof caps .
Our technicians replaced the electrical connectors with waterproof models and reconfigured the wires for more secure routing.
We then cleaned the blower and main filter , and checked the static pressure to ensure optimal airflow through the restored coil.
Final result: restored performance and increased safety
After restarting, the Lennox system displayed:
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A blown air temperature 11°C lower than the ambient air, a sign of efficient heat exchange.
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No trace of water under the plenum after 48 hours of observation.
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8% reduced electricity consumption measured via the customer panel.
The relieved owner has regained stable indoor comfort and peace of mind , knowing that his system is now leak-free and well protected against moisture.
AirGreen tips to prevent this type of problem
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Have your coil inspected annually to prevent slow leaks.
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Clean the condensate drain regularly , especially during the summer.
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Ensure electrical connections are secure and insulated from moisture.
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Watch for rust or water stains around your unit: these are often the first signs of an underlying problem.
AirGreen expertise in Sainte-Rose and throughout Laval
Our services aren't limited to breakdowns. Every service call is an opportunity for us to restore the reliability and performance of your HVAC equipment, whether it's a Lennox, Fujitsu, Midea, Gree, or Trane heat pump.
Our certified technicians operate in Laval, Montreal, Longueuil, the North Shore and the South Shore , with the same commitment: precise, sustainable and transparent service.
At AirGreen , we believe that maintenance done well today prevents a costly breakdown tomorrow.