Accurate diagnosis on a flat roof: expert intervention from AirGreen
At AirGreen , we are regularly called to diagnose and repair HVAC systems installed on flat roofs, a common configuration in residential and commercial buildings on the North Shore . On this day, our team went to Sainte-Thérèse for a repair of a Sharp wall-mounted heat pump , whose outdoor compressor was installed on the roof of an apartment building.
Context of the intervention
The customer contacted us after noticing that the heat pump hadn't been heating properly for several days. Despite recent maintenance, the system was only producing lukewarm air, and the indoor temperature remained uncomfortable. This type of symptom could be due to several causes: refrigerant leak, overloaded compressor, or an electrical problem with the control board.
On site, we observed an installation of two Sharp wall-mounted units mounted on treated wood supports, securely fixed to the flat roof of the building. The condensers were connected to well-insulated refrigeration lines and connected to a brick wall where the power and communication cables ran.
Step 1 – Visual Inspection and Electrical Checks
We started with a complete inspection:
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Check the power supply and the dedicated circuit breaker.
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Check the connection box and cables connecting the heat pump to the interior.
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Observe for signs of oil on the fittings to detect a possible refrigerant leak .
No signs of leakage were observed, but the compressor would not start despite a heat call from the indoor unit. Analysis of the control module revealed correct voltage but a faulty electronic board , preventing the start signal.
Step 2 – In-depth diagnosis: electronic card failure
Using our multimeter and a proprietary Sharp communication tool, we confirmed that the compressor PCB was no longer responding. This type of failure is common on units exposed to repeated freeze-thaw cycles on Quebec's flat roofs. Humidity and temperature fluctuations often accelerate internal circuit corrosion.
We immediately checked the availability of the part. Through our network of authorized Sharp suppliers , we were able to order a replacement board compatible with the AY-XU1 series.
Step 3 – System Replacement and Calibration
A few days later, once the part was received, our technician returned to the site to carry out:
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Safe disconnection of the unit.
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Complete replacement of the PCB board .
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Reprogramming the control module to Sharp series specifications.
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A cold start test and a complete cycle in heating mode.
The heat pump restarted without error, and the discharge temperature reached 39°C in just 5 minutes , proof of optimal operation.
Step 4 – Final Checks and Recommendations
Before leaving the premises, we have:
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Cleaned the exterior coils.
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Checked the refrigerant charge.
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Inspected the wooden supports for stability.
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The customer is advised to schedule a preventive inspection every spring , to avoid moisture accumulating in the connections.
Result
After our intervention, the Sharp HVAC system was operating at full capacity again, restoring consistent indoor comfort for the occupants. The client particularly appreciated our speed of intervention , our transparency regarding the diagnosis , and the care taken in calibrating the equipment.
In summary
This repair demonstrates the importance of:
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A precise diagnosis before any part replacement.
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Expert intervention capable of combining electrical and refrigeration skills.
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Regular maintenance , especially for units installed on flat roofs in Greater Montreal.
At AirGreen , we put our expertise at your service to extend the life of your Sharp, Fujitsu , Gree , Midea and many other heating and air conditioning systems . Whether you are in Montreal , Laval , Longueuil , on the North Shore or the South Shore , our specialized teams intervene quickly to diagnose, repair and maintain your HVAC systems, with guaranteed and lasting results.
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Sharp heat pump repair Sainte-Thérèse, HVAC service North Shore, air conditioning maintenance Montreal, Sharp compressor repair Laval, HVAC electronic board diagnosis.