Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg, author of the RV Handbook and the managing editor of the RV Repair Club. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave discusses an RV furnace that won’t light.
We own a 2020 Minnie Winnie and pretty much love it. First couple of AZ winter uses the furnace worked perfectly. Now we are on an extended cross-country road trip and while in Colorado at high altitude we attempted to take the morning chill off with the furnace. The thermostat and blower fan seem fine but the burner does not fire up. Because of the young age of this unit I am wondering if it has a recall or bulletin on the furnace. TIA for any insight. —Don
To help identify what might be causing your furnace to not light, it’s important to understand the operation.
How the furnace operates
When the thermostat is set and calls for heat, the fan motor starts and blows air to clean out or exhaust the burner assembly. The fan speed needs to be high enough to raise the sail switch inside the fan cage. That closes the circuit and tells the module board it is OK to open the gas valve and spark to light the burner.
If your battery is low, the fan will still turn but not with enough force to raise the switch, so it’s deceiving to owners. Even if you are plugged in to shoreline power, if your battery is sulfated, it will drop energy storage immediately and the converter may not kick in in a timely manner.
Another issue could be an obstruction in your vent lines or vents. If you have any vents closed or covered with rugs, this will restrict the air flow and cause a backup. That means the fan can’t lift the sail switch as well. Not sure if your Minnie has hoses like the photo or ducted vents under the floor with floor vents.
The first thing I would recommend is checking all the vents and lines inside the rig to make sure they are clear and allow air flow. Next listen for the click of the gas valve and a sparking attempt. If there is no spark attempt, then try boosting the battery with a portable battery charger/booster. If this does not help, the next step is to remove the fan cover and test the sail switch. This can be done with a multi-meter and push the sail switch up to check for a closed circuit.
Read more from Dave here.
Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. As the owner of Passport Media Creations, Dave has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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