Fault codes / RV furnace / 1 FLASH (3 s pause)

RV furnace: 1 flash (3 s pause)

What it means: Air flow / limit fault.

What to check

Check blower speed, return air, ducts, sail switch and limit switch. Measure 12V both sides of each.

Learn the system

• Furnace sequence
• LP system basics

Practice it on a service call

• Furnace blows cold
• Furnace sparks but never lights
• Furnace keeps shutting off, fan keeps blowing

Guided diagnosis

• Furnace
• Thermostat

Other RV furnace codes

• RV furnace: 2 flashes (3 s pause) Flame sense fault
• RV furnace: 3 flashes (3 s pause) Ignition lockout
• RV furnace: Steady on Internal control failure

Full field guide: Suburban and Atwood (Dometic) furnace board

Codes come from the maker manuals and public service sheets. Your model's own chart always wins, and LP and 120 volt work belongs to a qualified technician.