Complex electronic failure diagnosed in the field
At AirGreen , every service call is an opportunity to demonstrate our expertise in residential HVAC system repair . This time, we were called to the Rosemont–La Petite-Patrie neighborhood in Montreal , for a Midea central heat pump that had completely shut down. The customer reported that after a brief power outage, the system would not restart, despite several reset attempts.
Context of the intervention
The residence, typical of the Rosemont area, was equipped with a 36,000 BTU Midea central heating system, installed about five years ago. The outdoor unit, protected by a partial weather shelter, was displaying an error code on the main board. This type of electronic alert often indicates a problem with the control board or power supply .
Our team attended the site with full electronic diagnostic equipment to avoid any unnecessary component replacements.
Detailed diagnosis
Upon opening the top panel of the outdoor unit, our technicians noted:
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Traces of humidity and light corrosion on the main electronic board (PCB) .
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An internal fuse on the power module has blown .
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Oxidized control wires , probably due to water infiltration via the protective sheath.
After checking the input voltage and continuity of the power line, we were able to confirm that the compressor and fans were intact . The problem was indeed with the control board.
Steps of repair
1. Replacing the fuse and cleaning the board
We started by replacing the 3.15A fuse and thoroughly cleaning the circuit board with a specialized anti-static product. This restored some of the power signal, but the module remained unstable.
2. Analysis of communication circuits
While testing the interface board connectors, we detected a partial short circuit on the communication bus between the power board and the logic board. This type of fault prevents the system from synchronizing commands between the indoor and outdoor units.
3. Replacement of the original Midea power board
We then proceeded to completely replace the electronic card with an original Midea part, recalibrating the communication parameters according to the serial number of the compressor.
4. Controlled restart and recalibration
Once the replacement was completed, we powered the system back up and ran a full start-up cycle in heating mode . Operating pressures, discharge temperature, and compressor current quickly stabilized, confirming full system restart .
Results of the intervention
The client immediately found comfort in his home, with consistent heating and quiet operation. We took advantage of the visit to recommend:
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An annual inspection of electronic boards and electrical connections.
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Preventive cleaning of the area around the outdoor unit , to prevent moisture or debris from compromising the circuits.
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Installing a newer, waterproof outdoor circuit breaker to reduce the risk of power surges.
AirGreen Expertise
This repair demonstrates the growing complexity of modern HVAC systems. Midea central heat pumps are renowned for their energy efficiency, but they require advanced technical expertise when performing electronic repairs. Our RBQ and CCQ -certified technicians are trained to accurately diagnose this type of fault without resorting to expensive part replacement.
We also checked the indoor wall control board , which had registered an E6 communication error—typical of link faults between boards. After a full reset, the system operated normally.
Technical assessment
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Brand: Midea
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Type: 36,000 BTU central heat pump
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Problem: Electronic failure (defective main board)
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Solution: PCB replacement, system recalibration, cleaning and checking connections
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Result: Complete restoration of heating and cooling
Conclusion
At AirGreen , every repair is carried out with rigor and transparency. Our goal is always to maximize the lifespan of your HVAC system while ensuring optimal comfort. Thanks to a targeted and methodical intervention , we allowed this Rosemont–La Petite-Patrie homeowner to regain a perfectly functional system , without unnecessary additional costs.
If your central heat pump is showing signs of weakness—sudden shutdown, flashing light, or no start—call our experts. We respond quickly in Montreal, Laval, Longueuil, and on the North Shore and South Shore , with a clear diagnosis and lasting solutions.