Suburban 520840 Wiring Harness – NT-S & NT-SE Furnaces (For Use with 521099 Board) – Special Order

Product Overview

The Suburban 520840 Wiring Harness is designed specifically for Suburban NT-S and NT-SE series RV furnaces, allowing proper integration with the 521099 ignition control board to enable fan control functionality.

This harness is required when upgrading furnaces that did not originally include fan control wiring. It ensures proper communication between furnace components and allows the 521099 board to operate the blower system efficiently.

Ideal for restoring or upgrading your furnace system, the 520840 harness helps maintain reliable operation and prevents wiring issues during installation.

Key Features

• Designed for Suburban NT-S and NT-SE series furnaces
• Enables fan control functionality when used with control board 521099
• Required for upgrading systems without fan control
• Provides secure and reliable wiring connections
• Helps ensure proper furnace operation and efficiency
• Reduces risk of electrical issues and improper wiring
• Direct-fit design for straightforward installation
• Special Order Item – Estimated 7–14 day lead time

Specifications

• Part Number: 520840
• Product Type: Fan control wiring harness
• Application: Suburban NT-S and NT-SE series RV furnaces
• Function: Enables fan control integration with 521099 board

Compatible Furnace Models

Suburban NT-S Series

• NT-12S
• NT-16S
• NT-20S

Suburban NT-SE Series

• NT-12SE
• NT-16SE
• NT-20SE

Important Installation Note

This wiring harness connects to the Suburban 521099 ignition control board to activate the fan control feature.

• The 521099 module board is NOT included and must be purchased separately
• Required when upgrading furnaces that do not already have fan control wiring

When Do You Need This Harness?

You will need the 520840 wiring harness if:

• You are upgrading to the 521099 control board
• Your NT-S or NT-SE furnace does not have fan control wiring
• You are replacing damaged or missing wiring
• Your furnace fan does not function properly after a board upgrade

Why This Harness Matters

• Ensures proper communication between furnace components
• Allows full functionality of upgraded control boards
• Prevents wiring mismatches and installation issues
• Helps extend furnace life and reliability

FAQ

Do I need this with the 521099 control board?
Yes, if your furnace does not already have fan control wiring, this harness is required.

Is the control board included?
No, the 521099 module board is sold separately.

Will this fit all NT series furnaces?
No, this harness is specifically for NT-S and NT-SE series models listed above.

Is this item in stock?
This is a special order item with an estimated 7–14 day lead time.

Is installation difficult?
No, this is a direct-fit harness designed for straightforward installation.