Suburban 233484 Limit Switch for NT Series Furnaces (Replaces 233020)

The Suburban 233484 high-limit switch is the OEM safety cutoff used on select NT-Series RV furnaces. It opens on high temperature to prevent overheating and nuisance damage, then automatically resets once the heat exchanger cools. This part supersedes or is referenced by older number 233020.

Compatibility

• NT-20S, NT-20SQ, NT-20S-TC (above serial no. 093800203)
• NT-16S (above serial no. 093900001), NT-16SQ
• NT-16SE (above serial no. 094100427), NT-16SEQ
• NT-20SE (above serial no. 094000057), NT-20SEQ

Always verify furnace model and serial number against the list above before ordering.

What this does

• Monitors heat exchanger temperature and opens (cuts power) if temp exceeds the set point.
• Protects furnace from overheating; restores operation once safe temp is reached.

Specs

• Type: High-limit disc switch, auto-reset
• Mounting hole spacing: 1-5/8" (approx.)
• Fitment family: Suburban NT-Series (see list above)
• Warranty: 90-day manufacturer limited

Includes

• (1) Suburban 233484 limit switch
• Factory crimp terminals preinstalled (where applicable)

Installation notes

1. Disconnect 12V power and shut off LP gas. Allow furnace to cool completely.
2. Access the limit switch on the hot-air housing. Transfer wires one-for-one.
3. Re-use OEM mounting screws; verify unobstructed airflow and a clean return to prevent repeat trips.

Basic DIY skill required. If the switch trips repeatedly, diagnose airflow restrictions, blower performance, ducts, and return filter/obstructions.

Replaces / Cross-Refs

• Suburban: 233484, 233020 (ref#)

Common symptoms of a failed or tripping limit

• Furnace lights then shuts down after a short run
• 12V call for heat present but burner won’t stay lit
• Visible dust/debris or crushed ducting causing low airflow