Lennox Furnace: Program the unit size code on a replacement furnace control
Program the unit size code on a replacement furnace control on a Lennox furnace: A replacement control needs the furnace size code stored; three bars then E203 at power-up means no valid code.
Applies to: All EL296UHV models: EL296UH045XV36B, 070XV36B, 090XV36C, 090XV48C, 090XV60C, 110XV48C, 110XV60C, 135XV60D
How to fix program the unit size code on a replacement furnace control: step by step
- Thermostat OFF and control idle.
- Hold the button until a solid P shows, then release.
- Hold the button again and release when the right size code shows.
- Within 10 s hold the button for 5 s to store it.
- Cycle 24 V power to confirm the code was saved.
If the unit shows an error code, look it up: Lennox Furnace codes
Models
EL296UH045XV36BEL296UH070XV36BEL296UH090XV36CEL296UH090XV48CEL296UH090XV60CEL296UH110XV48CEL296UH110XV60CEL296UH135XV60D
Source: Lennox EL296UHV(X) Unit Information, Corp 1125-L5 (rev. 03/2022), IX Program Unit Capacity Size Modes, p.110 (printed p.109). 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.