OEM Lennox Pressure Switch — 93W86

The genuine OEM Lennox 93W86 pressure switch is a critical safety control in your Lennox gas furnace. It monitors negative pressure created by the draft inducer to verify that the combustion venting system has proper airflow before the ignition sequence is allowed to begin. If the switch does not sense adequate draft, it prevents the gas valve from opening — protecting your home from unsafe combustion conditions.

Common failure symptoms: A failing 93W86 pressure switch often causes the furnace to lock out and refuse to light, short-cycle, or throw a pressure-switch fault code on the control board. You may hear the inducer motor start but the burners never ignite, or the system repeatedly trips on a safety error. Cracked tubing, a stuck diaphragm, or corroded contacts inside the switch are frequent culprits.

Why OEM matters: Pressure switches are calibrated to a specific trip point measured in inches of water column. Using the factory-specified Lennox 93W86 ensures the switch actuates at the exact pressure your furnace was engineered for, preserving safe operation and proper venting. Generic substitutes may have incorrect set points that cause nuisance lockouts or, worse, allow operation under unsafe conditions. Insist on genuine OEM for reliable, code-compliant performance.