EE8 High-stage pressure switch closed at start of heating cycle

What the control is telling you

On a two-stage furnace the high-stage pressure switch circuit is already closed at the start of a heat call. The furnace runs on low stage only (inducer still operates). Flowcharts call this code E8.

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

Likely causes

• High-stage pressure switch contacts stuck closed
• Short in the pressure switch circuit wiring

Test and repair steps

1. Power off, remove the wires from the high-stage pressure switch and ohm the contacts with the inducer off - they must be open.
2. Replace the high-stage pressure switch if the contacts are closed with no vacuum.
3. If the switch is good, find and repair the short in the switch wiring.
4. Retest a high-fire call (W1+W2) and confirm the furnace stages up.

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

• 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
• EE9 High-stage pressure switch did not close
• EAF R-32 sensor communication lost - mitigation mode
• EAL R-32 refrigerant leak detected - mitigation mode
• EAS R-32 sensor fault - mitigation mode