Lennox SLP98UHV Error Code A: Indoor Blower CFM Setting
What Does Code A Mean?
The letter A on the Lennox SLP98UHV display indicates the indoor blower CFM (cubic feet per minute) setting readout. This appears when the diagnostic push button on the control board is pressed, cycling through the available diagnostic information. The display alternates between showing the letter A and the current CFM value.
This is not an error code — it is a diagnostic tool used by HVAC technicians to verify the blower is configured for the correct airflow. The CFM setting determines how much air the blower moves through the ductwork, which affects both heating performance and comfort. Different operating modes (heating, cooling, continuous fan) may have different CFM settings.
No action is required if you see this display. It will return to the normal idle display after the diagnostic button cycle completes. If you did not press the diagnostic button and the display is showing A, someone else may have accessed the diagnostics, or the button may be sticking.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Diagnostic push button pressed to view blower CFM settings | Most common | — |
When to Call a Professional
Contact a licensed HVAC technician if:
- You suspect the blower airflow is set too high or too low for your duct system
✓ Verified against manufacturer service manual — March 2026