ST9120C Furnace Fan Control Board Replacement for Honeywell Furnace Fan Control Circuit Board ST9120C

Description

Product Overview

The DDORUU ST9120C furnace fan control board is engineered as a precise, drop‑in replacement for Honeywell blower control circuits. Constructed from high‑temperature resistant polymer and copper‑clad circuitry, the board tolerates the demanding environment of residential and light‑commercial furnaces. It measures 6.29 x 5.09 x 1.57 inches and weighs only 7 ounces, making it easy to handle during installation. The 24‑volt control circuit is protected by a replaceable 5 A automotive‑type fuse, ensuring safe operation under both 120 V and 240 V power supplies. Maximum blower loading is 15 FLA (30 LRA) at 120 V and 7.5 FLA (15 LRA) at 240 V, while the inducer can handle up to 3 FLA (10 LRA) at 120 V or 1.5 FLA (5 LRA) at 240 V. Humidifier and electronic air cleaner terminals are each rated at .8 A @ 115 V, providing flexibility for additional HVAC accessories.

Usage

This control board is ideal for homeowners, HVAC technicians, and contractors who need a reliable replacement part for Honeywell furnace models that use part numbers 40403‑001, 40403‑002, 40403‑003, or the ST9120 series. It works seamlessly in forced‑air heating systems, air‑conditioner heat pumps, and combined HVAC units where precise fan speed regulation is critical for comfort and energy efficiency. The board’s universal voltage capability allows it to be used in both North American 120 V residential installations and 240 V commercial setups. Its compact footprint fits standard furnace enclosures without requiring any modifications to the existing wiring harness.

Why Choose Us

Choosing the DDORUU ST9120C means selecting a component that combines durability, safety, and performance. The board undergoes rigorous quality testing, including thermal cycling and overload protection verification, to meet industry standards. Unlike generic knock‑offs, this unit includes a replaceable 5 A fuse that can be serviced on‑site, reducing downtime. Our after‑sales support offers technical assistance and a clear warranty policy, ensuring you have confidence throughout the product’s lifecycle.

Key Features

• Direct replacement for Honeywell 40403‑001/002/003 and ST9120 series, eliminating the need for custom wiring.
• Supports up to 15 FLA blower load at 120 V, providing strong airflow for larger homes.
• Integrated 5 A replaceable fuse protects the 24 V control circuit from overloads.
• Compact, lightweight design (7 oz) simplifies installation in tight furnace bays.
• Dedicated customer support and technical assistance for quick troubleshooting.

FAQ

Is this board compatible with all Honeywell furnace models?

It is compatible with Honeywell models that use part numbers 40403‑001, 40403‑002, 40403‑003, as well as the ST9120A, B, and C series. Always verify the existing board’s part number before purchase.

Can the board be used on a 240 V system?

Yes. The ST9120C is rated for both 120 V and 240 V operation. When installed on a 240 V system, the maximum blower load is reduced to 7.5 FLA (15 LRA) to maintain safe operating temperatures.

What is the procedure for replacing the fuse?

The board includes a socket for a standard 5 A automotive fuse. To replace it, power down the furnace, locate the fuse holder on the board, remove the old fuse, and insert a new 5 A fuse of the same type. Re‑energize the system and verify normal fan operation.

Does the board support humidifier and electronic air cleaner connections?

Yes. Both the humidifier terminal and the electronic air cleaner terminal are rated at .8 A @ 115 V, allowing you to connect common residential humidifiers and air cleaners without additional relays.

What warranty does DDORUU provide for this product?

The board is shipped with a standard 90‑day limited warranty covering manufacturing defects. For any issues within this period, contact our support team for a replacement or repair.