A complex intervention on a central unit in a closed technical room
At AirGreen , we were recently contacted for a service call in Saint-Eustache , on the North Shore of Montreal , concerning an ACD central unit installed in a concrete technical room . The client, the manager of a small commercial building, noticed a complete failure of the system : no start-up of the compressor or the fan, and the wall display remained black.
This situation required rapid and methodical intervention, as the system served several offices where the interior temperature exceeded 28°C.
Diagnosis: Power failure and damaged wiring section
Upon our arrival, our technician checked the safety and power components . The main circuit breaker appeared intact, but the lack of voltage at the ACD module input immediately pointed our investigation toward the internal power circuit .
Upon opening the condenser electrical panel, our team noticed:
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A section of oxidized wiring at the main terminal block (L1/L2).
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Traces of overheating and blackening on a connector.
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Improper tightening of the terminals , causing intermittent electric arcs.
This type of problem is common in closed and poorly ventilated technical rooms, especially when dust accumulates and thermal cycles cause repeated expansion of the wires.
Repair steps: securing, replacing and recalibrating
Our technicians undertook the repair following AirGreen's rigorous safety procedures :
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Complete power cut off via the main circuit breaker.
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Disassembly of the defective terminal block and cleaning of carbon deposits.
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Complete replacement of oxidized wiring , with heat-resistant THHN approved conductors.
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Tightening calibrated to the exact torque according to ACD specifications to avoid any future micro-sparks.
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Checked the compressor relay and main contactor , which showed slight blackening: cleaned and tightened.
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Power up and sequence test : All components restarted normally, without noise or surges.
Once the electrical fault was eliminated, we carried out a complete performance diagnosis . The pressure and temperature values were within the manufacturer's tolerances, indicating that the compressor had not suffered any damage.
Results: stabilized system and enhanced security
At the end of the intervention, the ACD system was again operating at full capacity. Tests carried out over a 45-minute period confirmed:
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A stable voltage of 240 V between phases.
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Smooth compressor start-up , without voltage drop.
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A blowing temperature of 12°C, ensuring immediate comfort for occupants.
We also installed an ambient temperature sensor in the technical room to alert the customer in case of future overheating.
Analysis: the risks of an unventilated technical room
This case illustrates an often underestimated problem: insufficient ventilation of technical rooms . Even though ACD units are designed to withstand demanding environments, the heat accumulated in a closed room can:
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Degrade electrical connections ;
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Reduce the lifespan of components ;
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Increase the risk of short circuit ;
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And above all, cause intermittent stops that are difficult to diagnose.
Our technicians systematically recommend ensuring:
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A permanent fresh air intake ;
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A minimum space of 60 cm around the unit;
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And biannual preventative maintenance to clean and tighten electrical connections.
AirGreen: safe and certified electrical interventions
Working on central units like this ACD in Saint-Eustache requires extensive electrical expertise . Our technicians, certified in HVAC systems and building electricity, use calibrated diagnostic instruments to ensure the long-term safety and reliability of the equipment.
With our rigorous approach, we not only avoid immediate breakdowns, but we prevent future failures that could compromise the entire heating or air conditioning system.
Conclusion
This ACD HVAC system repair in Saint-Eustache demonstrates the critical importance of a thorough electrical inspection during a total outage. By replacing a simple damaged terminal block and recalibrating the connections, AirGreen allowed the customer to regain comfort and peace of mind , while ensuring the safety of their installation .
For any HVAC repair service in Montreal, Laval, Longueuil or on the North Shore, our team is available quickly to diagnose, correct and optimize your ACD, Goodman, Fujitsu, Gree, Midea, Lennox systems and many others.