Carrier LH33WZ520 Flame Sensor

The Carrier LH33WZ520 Flame Sensor is a critical OEM replacement part designed for combustion safety in gas-fired furnaces. This sensor operates via flame rectification, passing a small microamp signal through the burner flame to the integrated furnace control (IFC). When the silicon carbide igniter or hot surface igniter successfully lights the burners, this flame rod detects the presence of ions within the flame. If the furnace control board fails to receive this signal—often due to carbon buildup or oxidation on the stainless steel rod—it will initiate a safety lockout, shutting down the gas valve to prevent unburned fuel accumulation. This specific HVAC flame sensor features a 70-degree bend and is a direct-fit component for various Carrier, Bryant, and Payne models, including the PG9MTAV and PG9YAA series. Utilizing a genuine Carrier part ensures proper microamp signal strength and avoids the impedance issues common with generic aftermarket furnace parts.

• Precise Rectification: Engineered to provide a consistent microamp signal to the furnace control board, preventing nuisance limit switch trips or ignition failures.
• Exact Geometry: Featured 70-degree sensor bend and 1-7/8 inch extension length ensures the rod is positioned perfectly within the burner flame for rapid detection.
• OEM Durability: Constructed with high-grade Kanthal alloy or high-temperature stainless steel to resist thermal fatigue and soot accumulation during high-cycle operation.
• Plug-and-Play Compatibility: Ships with standard 1/4-inch spade connector for immediate integration into existing furnace wiring harnesses.

• What does a furnace lockout code for "Flame Sense Out of Sequence" mean? This is typically caused by a dirty flame sensor or a faulty gas valve. If the sensor detects a flame before the ignition sequence, or fails to detect it after 3-5 seconds of ignition, the IFC board will lock out for safety.
• Can I clean the LH33WZ520 instead of replacing it? While cleaning a flame sensor with fine steel wool or an abrasive pad can remove carbon deposits, persistent oxidation or cracks in the porcelain insulator necessitate a full replacement to ensure reliable furnace ignition.
• Does this fit all PG9 series furnaces? It is confirmed for PG9MTAV, PG9YAA, and PG9YAB series. Always verify the part number against the OEM parts list in the furnace service manual before installation.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.