OEM Lennox Limit Switch — 20J98

The genuine OEM Lennox 20J98 limit switch is a temperature-activated safety control that guards your furnace against dangerous overheating. Mounted to sense heat exchanger or plenum temperature, it opens the burner circuit whenever readings exceed the safe limit and helps command blower operation to dissipate built-up heat. In your Lennox furnace, this component is essential to safe, code-compliant heating cycles.

Common failure symptoms: When the 20J98 fails, you may see the furnace short cycling, tripping on a high-limit fault, refusing to ignite, or leaving the blower running nonstop. A switch stuck open produces no heat on a call, while one that trips too early cuts heating cycles short and leaves your home cold.

Why OEM matters: This is a life-safety part, so its trip point and electrical rating must exactly match your Lennox furnace's engineering. The factory-original 20J98 is calibrated to Lennox specifications for accurate overheat protection and dependable performance. Generic replacements with different setpoints can compromise safety or cause repeated nuisance trips. Choose genuine OEM Lennox for correct protection and a guaranteed fit.