A complex service call on a faulty Midea VRF system
At AirGreen , we were recently called to diagnose and repair a Midea VRF system installed in a commercial building in Saint-Laurent . This sophisticated and efficient system powers multiple zones from a single outdoor unit, providing precise temperature control in each space. However, like any complex HVAC system, it requires specialized expertise when a problem arises.
Symptoms observed by the client
The building manager contacted us after noticing several malfunctions:
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Some areas were no longer cooling properly.
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The system was randomly shutting down.
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Error messages appeared on the central controller, indicating faulty communication between modules .
Faced with these symptoms, rapid and methodical intervention was required.
Midea VRF System Diagnosis
Our certified technicians arrived on site with a full range of VRF diagnostic equipment: electronic pressure gauges, a multimeter, and a Midea-compatible service computer. Upon opening the control panel, several things caught our attention:
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Flashing warning lights on the main circuit board.
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Unstable supply voltage on one of the external modules.
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Traces of moisture near the control box, indicating possible infiltration.
Electrical and electronic verification
Using a digital multimeter , we measured the voltages on the main terminals and identified a fluctuation between 205 V and 235 V , a sign of an irregular power supply . This instability caused the inverter compressor to restart unexpectedly, leading to the system stopping.
Refrigerant Analysis and Working Pressures
We then connected a digital manifold to the refrigerant lines. The pressures observed were not in accordance with the nominal values of the Midea VRF series:
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Low pressure: 95 psi
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High pressure: 395 psi
These values indicated a slightly insufficient charge of R410A refrigerant , probably due to a microleak on an interconnect solder between two modules.
VRF System Repair and Recommissioning
1. Electrical stabilization
We first corrected the power fluctuation by tightening the connections in the secondary electrical panel and cleaning the oxidized terminals. A continuity test confirmed the restored stability.
2. Leak detection and repair
Using an electronic leak detector , we located a micro-leak on a flare fitting located near the liquid line. After evacuating the residual gas, we:
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Replaced the faulty fitting.
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Pulled a full vacuum to 500 microns .
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Recharged the system with the exact amount of R410A prescribed by the manufacturer.
3. Checking the control circuit
The power module (IPM) on the main board was showing signs of overheating. We replaced the module and reset the error codes using Midea service software.
Result: restored performance and optimal comfort
Once the system was rebooted, we noticed:
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Stable operation across all indoor units.
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Balanced and within specification pressures (120 psi / 420 psi).
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Communication restored between all VRF modules.
The manager immediately noticed an improvement in comfort and a reduction in noise . The Midea VRF system has returned to its original performance, with normalized energy consumption.
What this intervention demonstrates
This type of intervention perfectly illustrates the complexity and precision required to diagnose a VRF system. These systems rely on inverter compressor and electronic expansion technology, where each parameter must be rigorously adjusted.
At AirGreen, our team has the tools, training, and experience to:
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Quickly diagnose VRF communication failures.
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Repair electronic boards, power modules and refrigerant leaks.
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Ensure complete follow-up after repair to ensure long-term reliability.
Maintenance Tips for a VRF System
To avoid similar failures, we recommend:
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A complete annual maintenance , including checking electrical connections and operating pressures.
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Regular cleaning of the exchangers and filters of the indoor units.
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Infrared inspection of electronic boards to detect invisible overheating.
These preventive actions extend the lifespan of your installation and maintain constant comfort.
AirGreen: your HVAC partner in Montreal, Laval and throughout the metropolitan area
Whether it's a Midea VRF system , a Fujitsu central heat pump , or a Sharp wall-mounted air conditioner , AirGreen is recognized throughout Montreal, Laval, Longueuil, the North Shore and the South Shore for its expertise in HVAC repair, maintenance and installation .
Every service call is handled with the same rigor, precision, and commitment to providing the lasting comfort our customers deserve.