OEM Carrier Fan Timer Control Board 20054502 for Model PG8HAA048100AAJA

This OEM fan timer control board is the factory-specified replacement for the Carrier PG8HAA048100AAJA gas furnace. Made by Honeywell for Carrier (OEM part ST9120C2010), this board manages the sequencing of the inducer motor, hot surface igniter, gas valve, and circulator blower — coordinating every stage of the heat and fan cycle. When this board fails, you may experience a furnace that won't ignite, a blower that runs continuously or not at all, erratic fan timing, or a system stuck in lockout with no fault codes displayed.

• Specs: OEM Part # 20054502 | Honeywell ST9120C2010 | Fan Timer / Blower Control | Single-stage furnace application | 120V input | 24V control circuit | Replaces 20054501, ST9120A, ST9120B, ST9120C
• OEM vs Generic: This is the genuine factory OEM board — not a third-party substitute. OEM boards are factory-programmed with exact fan-on/fan-off delays and fault logic matched to your Carrier furnace. Generic boards may use different timing profiles that can reduce efficiency, increase heat exchanger stress, or void remaining equipment warranties.
• Install Difficulty: 3/5 — Requires shutting off 120V power and gas supply before beginning. Label all low-voltage wiring connections before removing the old board. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter for pre/post testing. Note and transfer any DIP switch settings from the old board before installation.
• Warranty: 1-year OEM manufacturer warranty. In stock and ships same business day from our warehouse.

Compatibility: Fits Carrier model PG8HAA048100AAJA gas furnace. This board is also cross-referenced to Ducane and Rheem applications using part 20054502. Always verify your existing board's part number against your unit's data plate before ordering. Have questions about fitment? Our HVAC parts specialists verify compatibility before you buy — contact us today and get your furnace back online fast.