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Daikin · Furnace

EE1 Pressure switch closed at start of heating cycle

Medium severity Daikin DR96TN/DD96TN

What the control is telling you

At the start of a heat call the (low-stage) pressure switch circuit is already closed before the inducer runs. The control will not start the ignition sequence. Flowcharts call this code E1.

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

Likely causes

  • Pressure switch contacts stuck closed
  • Short in the pressure switch circuit wiring (to another wire or to ground)

Test and repair steps

  1. Turn off power, remove the wires from the pressure switch and check the contacts with an ohmmeter while the inducer is off - they must be open.
  2. If the contacts read closed with no vacuum applied, replace the pressure switch (on two-stage furnaces this is the low-stage switch).
  3. If the switch is open, trace the pressure switch circuit wiring for a short to another wire or to ground and repair it.
  4. Reconnect, cycle the thermostat and confirm the code clears.

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Source: Daikin RSD6612304 (DR96TN/DD96TN service), 2 Stage Troubleshooting Codes, p.28-29; Error Code E1, E2, E8, E9 flowchart p.36. Summarized in our own words; check the original manual for your model.

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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.