Lennox Heat Pump: Two horizontal lines on display (soft disable) – Lennox communicating

Updated October 13, 2026 · by Aurora Star Tech Inc.

Two horizontal lines on display (soft disable) - Lennox communicating on a Lennox heat pump: The control shows two horizontal lines on its 7-segment display (damper module or EIM: green LED 3 s on / 1 s off). The thermostat found a device it does not recognize and put it in soft disable; the thermostat itself shows no alert code for this (often alert 10 is logged).

Homeowner with a heat pump problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Applies to: Lennox communicating heat pumps incl. variable-capacity inverter units in S30/S40 smart thermostat systems

Common causes of two horizontal lines on display (soft disable) - lennox communicating

Control board was replaced and the system was not reconfigured
New device added after commissioning
Device on the bus not communicating with the thermostat

How to fix two horizontal lines on display (soft disable) - lennox communicating: step by step

Confirm wiring between all devices (thermostat/smart hub, indoor, outdoor, damper module, EIM).
Cycle power to the control that shows the soft disable.
Reconfigure. S30: go to Menu > Settings > Advanced Settings, open View Dealer Control Center, then Equipment > Reset All Equipment. S40: go to Menu > Settings > Advanced Settings, open View Service Support Center, then Equipment Setting > Reset and pick Reset HVAC Equipment.
Run the thermostat setup again so it auto-detects every device.
Check the device's installation/setup guide if it stays disabled.

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

If the unit shows an error code, look it up: Lennox Heat Pump codes

Models

Lennox EL16KP1

EL16KP1-018 EL16KP1-024 EL16KP1-030 EL16KP1-036 EL16KP1-042 EL16KP1-048 EL16KP1-060

Lennox ML14KP1

ML14KP1-018 ML14KP1-024 ML14KP1-030 ML14KP1-036 ML14KP1-042 ML14KP1-048 ML14KP1-060

Source: Lennox Alert Code Guide (V2) 100017, 3. Soft Disable, p.6; Lennox SL280UHNV Unit Information Corp 1601-L8 (rev 04/2024), Soft Disable, p.15. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.