EE1 Pressure switch closed at start of heating cycle

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.

Settings for these units

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

These are normal operating displays, not fault codes.

Models that show this code

13 models in Daikin DR96TN/DD96TN

Other codes on the same units

• E10 Grounding fault / poor neutral connection
• E11 Flame rollout switch open
• EE0 Lockout - too many ignition retries (3)
• EE2 Pressure switch did not close (inducer runs, no ignition)
• EE3 High (primary) limit open
• EE4 Flame sensed with no call for heat
• EE5 Open fuse (short in low voltage wiring)
• EE6 Low flame signal