A17
IVT
Control communication failure
Furnace shows communication error between user interface and main control; display may be blank or show dashes
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Loose communication cable, Damaged display module, Faulty IVT main control board, Incorrect bus wiring polarity
How to Fix / Troubleshooting
Safety: Turn off power before unplugging any control cables.
- Check display power: Confirm that the display or room controller is receiving power (backlight or LEDs). If completely dead, the module or its power feed may be faulty.
- Inspect communication cable: Locate the low-voltage cable between the IVT main control and the user interface. Ensure both ends are fully seated and not corroded.
- Check polarity: For bus systems with +/− terminals, verify that polarity is consistent at both ends according to the IVT wiring diagram.
- Swap controller (if available): If you have a known-good IVT room controller, temporarily connect it to see if communication is restored.
If wiring and controller are good, the main control board may require replacement by an authorized IVT service provider.
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Repair Difficulty
Hard
4/5
Required Part
IVT main control board
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