OEM Lennox Pressure Switch w/ Bracket — 88K90

The genuine OEM Lennox 88K90 pressure switch, supplied complete with its mounting bracket, is a critical safety control that verifies proper draft and venting in your Lennox furnace before the burners are allowed to ignite. It monitors the negative pressure created by the draft inducer motor and confirms that combustion gases are being safely exhausted — if adequate airflow isn't detected, the switch prevents ignition to protect against dangerous flue blockages.

When a pressure switch fails or a venting problem exists, the furnace typically locks out and refuses to fire, short cycles, or throws a fault code for an open or stuck pressure switch. A cracked hose, clogged port, weak inducer, or a switch stuck open or closed are all common culprits behind a furnace that ignites briefly then shuts down.

The OEM 88K90 is calibrated to the precise pressure set point (measured in inches of water column) your Lennox furnace requires, and the included bracket ensures correct positioning. A generic switch with the wrong trip point can cause nuisance lockouts or, worse, defeat a vital safety function — making this exact-fit factory replacement the reliable choice for safe, code-compliant operation.