Repaired Lennox EL296V two-stage furnace with no heat complaint in Denton. Diagnosed failed pressure switch using digital manometer. Replaced switch with OEM part 103935-03. Cleaned flame sensor with fine-grit sandpaper. Verified inducer motor operation. Checked all limit switches. Adjusted blower speed for proper temperature rise. Cycled system through both stages to ensure proper operation. Restored heat to residence.