EE6 Low flame signal

What the control is telling you

The furnace runs normally but the flame-sense current is weak. If it keeps dropping the furnace will start losing flame and locking out.

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

Likely causes

• Flame sensor coated or oxidized
• Flame sensor not positioned correctly in the flame
• Lazy burner flame from wrong gas pressure or poor combustion air
• Poor ground

Test and repair steps

1. Put a DC microamp meter in series with the flame sensor wire and run a heat cycle: normal is 1 to 4 microamps.
2. Clean the flame sensor with steel wool (an invisible coating acts as an insulator) and check that it sits in the flame.
3. Check the burner flame it should be stable, soft and blue, not lifting or yellow.
4. Compare manifold and inlet gas pressure with the rating plate and adjust if needed.
5. Inspect the combustion air intake pipe is it blocked, and are its length, elbow count and termination correct?
6. Check high-resistance connections and grounding in the flame sense circuit.

Settings for these units

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