520840 Suburban RV furnace FAN CONTROL WIRING KIT, NT12-20

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The 520840 Suburban RV Furnace Fan Control Wiring Kit (NT12–20 Series) is the OEM wiring harness and control‑interface kit used on Suburban’s NT12, NT16, and NT20 furnaces. It provides the correct factory wiring layout, connectors, and control logic needed for proper blower operation, ignition sequencing, and thermostat communication in the smaller NT‑series furnaces. This kit is essential when replacing an older NT12–20 furnace, repairing heat‑damaged wiring, or correcting miswired systems that cause blower‑only operation or failed ignition.

It restores OEM‑correct connections between the thermostat, limit switch, sail switch, time‑delay relay, and ignition board, ensuring the furnace runs through its heat cycle safely and reliably. Technicians rely on this kit to bring compact NT‑series furnaces back to proper operation without guesswork.

What the 520840 Kit Supports

• OEM wiring harness for Suburban NT12, NT16, and NT20 furnaces

• Ensures correct blower start‑up and shutdown timing

• Provides proper connections for limit switch, sail switch, ignition board, and relay

• Prevents miswiring that causes no‑heat, blower‑only, or short‑cycling issues

• Designed specifically for NT12–20 models (not universal)

• Ideal for furnace replacements, rebuilds, or restoring damaged wiring