Where is the RV furnace reset button? (Most don’t have one)

Common symptoms

• You are looking for a red reset button on the furnace and cannot find one.
• The furnace tried to light, gave up, and now the fan will not come on at all.
• The fan runs and runs, but only cold air comes out.
• The fan ran about 30 seconds after you turned the heat on, then stopped.
• A small light on the furnace control board is flashing.
• The furnace quit when the propane ran out and will not restart after the refill.

Quick checks before anything else

• The thermostat is on Heat and set a few degrees above room temperature.
• The on/off switch on the furnace itself is on.
• The furnace fuse or breaker on the 12V panel is good.
• The battery reads about 12.6 volts at rest.
• The propane tank has gas, its valve is fully open, and a stove burner lights.
• The outside furnace vent is clear of nests, snow and covers.

Is there a reset button on an RV furnace?

Usually not. The Suburban, Atwood and Dometic DF furnace manuals we read describe no reset button. What these furnaces have is a lockout: after failed tries to light, or after a safety switch stays open too long, the control board shuts off the gas and stops trying. You clear a lockout at the thermostat, and on many models with the power switch on the furnace.

When people search for the reset button, they usually mean one of these:

• A lockout reset. This is the one most people need, and the thermostat does it.
• The furnace power switch. A small on/off switch on the furnace. Turning it off and on clears a hard lockout on Atwood furnaces.
• The limit switch. A heat-sensitive safety switch that shuts off the gas if the furnace overheats. In the Suburban sequence we read, the board waits up to 5 minutes for it to close again as the furnace cools. There is nothing to press.
• A house furnace button. Many online guides describe a red reset button on a home furnace. Sealed 12V RV furnaces are built differently.

One exception worth knowing: Dometic’s DF series manual lists a “furnace-installed breaker switch” that may be tripped or off when the blower will not turn on. Dometic’s advice for that case is to contact an authorized service tech.

What makes an RV furnace lock out?

• No flame after three tries Empty tank, a partly closed valve, or air in the gas line after a refill. The board tries three times, then quits.
• Airflow not proved On Suburban fan control boards, if the sail switch (a paddle that moving air pushes closed) stays open 30 seconds after the blower starts, the board locks out. Low voltage and lint are the usual reasons.
• Overheating If the limit switch stays open for 5 minutes, a Suburban fan control board locks out. Blocked return air and crushed ducts cause it.
• Flame lost The burner lights, the board cannot sense the flame, and it shuts down. On Atwood this is a hard lockout.
• Gas switch off On Suburban SF VHQ models, starting the furnace with its valve shut-off switch off makes the motor run 30 seconds, then the furnace locks out.

Step-by-step: how to reset an RV furnace

A reset only gives the furnace another set of tries. If the reason it locked out is still there, it will lock out again, so we fix the cheap causes before we reset.

1. Fix the cheap causes first Open the tank valve fully and light a stove burner. After a refill, let it run until the flame is steady, because air in the line is a common reason for a lockout. Suburban rates its furnaces for 10.5 to 13.5 volts, so check the battery too.
2. Turn the thermostat off Move it to Off, or to the lowest setting and then Off. Suburban’s service manual says turning the thermostat off is what clears the lockout on its boards. On older Suburban time-delay models, the blower keeps running in lockout until you do this.

   

3. Wait for the blower to stop Suburban says that once the blower has stopped, the ignition sequence can start again. Its lighting instructions allow about 2 minutes for the blower to go off. Dometic’s DF manual says to leave the thermostat off for at least 10 seconds.
4. Turn the furnace power switch off and on On Atwood furnaces, a hard lockout clears at the thermostat or by turning the power switch off and back on. Atwood puts the switch behind the outside access door, or on the left front side of the furnace on models with no outside door. Dometic DF door models have it inside the door, and LD or small-vent models have it on the outside of the furnace. Suburban’s SF VHQ manual says to cycle the thermostat or the unit power.

   

5. Set the thermostat back to Heat Set it a few degrees above room temperature. The fan may not start right away: Suburban’s SF manual says to allow about 30 seconds for the motor to start, and Atwood mentions a slight delay before the blower comes on.
6. Listen to one full try On a Suburban you should hear the blower, about 15 seconds of plain fan noise (the purge), fast ticking from the spark for up to about 7 seconds, then a soft whoosh. Atwood says to allow 30 seconds after the blower starts for the burner to light. If you hear ticking and no flame, read our guide to an RV furnace clicking but not igniting.
7. Read the LED if your furnace has one Atwood and Dometic boards flash a code. Dometic says the LED sits at the center of the control board. Some installs let you see it, some do not. The code tells you what to fix before the next reset (see the brand section below).
8. Stop after three tries Atwood says that after three attempts with no ignition you should shut the furnace down and contact a dealer or RV service shop, and not keep cycling it through the thermostat. Dometic allows up to three resets when air in the propane line is the cause. If it keeps failing, the cause needs finding, not another reset.

Suburban vs Atwood vs Dometic DF: how the reset differs

Suburban. The service manual we used gives no blink codes for these boards, so you work out the cause from what the furnace did before it quit. A fan that stops after about 30 seconds points to the sail switch. Heat that stops after a few minutes points to the limit switch. Ticking with no flame points to gas or spark.

Atwood. The board LED flashes with a 3-second pause between codes. Steady on means a board failure (hard lockout). One flash means a limit switch or airflow problem (soft lockout). Two flashes mean a flame sense fault (hard lockout). Three flashes mean an ignition lockout, a soft lockout that the board retries after one hour.

Dometic DF. The current manual keeps the same first four codes and adds two: four flashes for high voltage (16 to 17 volts) and five flashes for low voltage (8 to 9 volts). A low-voltage code points you to the battery and charger, which our battery not charging guide covers. If the code is on your wall thermostat instead of the furnace, see Dometic thermostat error codes.

When to call an RV tech

• The furnace locks out again after three resets.
• An Atwood or Dometic LED stays on steady, or keeps repeating the two-flash code.
• Dometic’s furnace-installed breaker switch has tripped.
• It locks out on the limit switch even with the return air and vents clear.
• You smell gas, see soot, or a CO alarm sounds at any point.

For how the furnace parts work together, see our RV furnace repair guide.

Common questions