Lennox EL296UHV Error Code d: Dehumidification Mode
What Does Code d Mean?
The lowercase "d" on the Lennox EL296UHV (blinking about 1 second on, 1 second off) indicates the icomfort system has engaged dehumidification. In this mode the control deliberately slows the variable-speed ECM blower's CFM so the cooling coil runs colder and pulls more moisture out of the passing air. The reduced CFM is shown after the "d".
Because the EL296UHV has a communicating, variable-speed blower, it can trim airflow precisely for humidity control, something a fixed-speed blower cannot do. This is why the furnace control participates in dehumidification even though it is a heating appliance: it owns and drives the indoor blower.
Do not confuse the lowercase "d" (dehumidification) with "dF" (a defrost cycle on a paired heat pump) or the lowercase "h" (heat-pump heat). Each lowercase indicator is a distinct normal operating mode on this SureLight control.
What You'll Notice
- The display shows a lowercase "d" followed by a CFM number while the air conditioner runs.
- Airflow from the vents feels lower than in normal cooling, because the blower is intentionally slowed to remove more moisture.
How This Is Diagnosed
The "d" plus CFM readout confirms dehumidification is engaged and the blower has been slowed on purpose, so it represents normal humidity control. It would only matter if "d" stays engaged constantly and airflow is so low that comfort suffers or the indoor coil begins to frost.
- Dehumidification mode stays engaged continuously and the reduced airflow leads to a frozen indoor coil or noticeably weak cooling.
- The system shows "d" but indoor humidity never drops, which suggests the humidity setting or a sensor needs attention.
Frequently Asked Questions
What is the "d" code on my Lennox furnace?
It shows that icomfort dehumidification is running. The system slows the blower to wring more moisture out of the air, and the display reports that reduced CFM.
Why is airflow weaker when I see "d"?
The lower airflow is intentional in dehumidification. A slower blower lets the cooling coil run colder and remove more humidity from the air.
✓ Verified against manufacturer service manual — March 2026