Daikin · Furnace

EEH Twinning error

Low severity Daikin DR96TN/DD96TN

What the control is telling you

The twinning feature (two furnaces linked through the TWIN terminal) is not working.

Applies to: Daikin DR96TN (upflow/horizontal) and DD96TN (downflow/horizontal) two-stage 96% furnaces with 9-speed ECM motor, R-32 ready

Likely causes

Twin wiring loose or wrong
Furnaces not the same model or set differently
Furnaces powered from opposite panel legs
Control board fault

Test and repair steps

Check the TWIN terminal wiring between the two furnaces and the thermostat wiring per the twinning diagram.
Both furnaces must be the same model with the same staging and speed tap settings.
Each furnace needs its own 115 VAC supply, with L1 on the same panel leg: L1 to L1 between the furnaces must read 0 V.
If the wiring and settings are correct, replace the integrated control board.

Settings for these units

Normal status displays (7-segment) · Daikin DR96TN/DD96TN

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Source: Daikin RSD6612304 (DR96TN/DD96TN service), 2 Stage Troubleshooting Codes, p.28-29. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.