E7
Ruud
Accessory Control Fault (Dehumidifier/ERV/HRV)
Thermostat displays E7 and may not control dehumidification or ventilation correctly
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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
Miswired dehumidifier or ventilation relay to thermostat ACC terminals, Shorted accessory coil, Incorrect accessory configuration in thermostat setup, Failed accessory driver on thermostat PCB
How to Fix / Troubleshooting
Safety: Turn OFF power to the HVAC system and any connected accessories at the breaker.
- Identify accessory: Determine which accessory (whole-house dehumidifier, ERV, HRV, ventilation damper) is connected to the thermostat's accessory (ACC) terminals.
- Check wiring: Verify that the ACC terminals on the thermostat and the corresponding terminals on the accessory are wired according to the Ruud and accessory manuals. Look for shorts or reversed polarity if 24V is used.
- Isolate accessory: Disconnect the accessory wires from the thermostat ACC terminals. Restore power and see if E7 clears. If it does, the accessory or its wiring is at fault.
- Test accessory coil: With power OFF, measure the resistance of the accessory relay coil or control input. A dead short or open circuit indicates a failed accessory component that must be replaced.
- Thermostat driver: If E7 persists with no accessory connected, the thermostat's accessory driver circuit may be damaged. Replace the thermostat.
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Repair Difficulty
Medium
3/5
Required Part
Ruud EcoNet Smart Thermostat Assembly
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