RV Furnace Trouble Shooting
Warning: We recommend that only qualified technicians work on furnaces.
This list is a guide only, of the more common causes of furnace failure, it is by no means complete.
Electronic Ignition Models (DSI)
Before going through the list below, these items should be checked.
Power supply, DSI furnaces require 10.5 VDC to 13.5 VDC to operate.
Ducting, check for the correct number of unrestricted ducts and outlets.
Check the return air path, be sure it meets the required minimum sq. in.
RV furnaces are not approved for use with filters.
Hydro Flame furnace parts
Suburban furnace parts
Dinosaur Electronics ignition boards
Fan 50 Plus ignition board with fan control
LP Gas info and cold weather use
This is generic and applies to most DSI model furnaces.
sail switch - micro switch with an arm that extends into the blower air stream which closes when the blower reaches approximately 75% of its rated speed. Also called an air prover switch.
limit switch - safety switch, a normally closed switch that opens if it gets to hot, opening turns off power to the gas valve and ignitor boardfan switch - a normally open switch that closes at a preset temperature, causes the furnace to run for a short time after the thermostat opens, allowing the furnace to cool down.
time delay relay - same function as fan switch, only has its own heater, also used instead of a thermostat relay in newer models.
ignitor electrode - similar to a spark plug, 2 versions, 3 probe (remote sense) or 2 probe (local sense.)
ignition control board - when powered, initiates gas valve opening and spark sequence which lasts approximately 7 seconds. Older models are 1 try, thermostat must be cycled off for at least 10 seconds before another ignition cycle is attempted. Newer boards are 3 try, will attempt to ignite 3 times at approximately 60 second intervals.
Some furnaces now come with a fan control ignition board. Fan control boards will shut the blower down if ignition does not occur after 3 attempts. Some models will shut down the blower and wait an hour and recycle, if ignition does not occur the furnace is then shut down. Older DSI furnaces, with some exceptions can be upgraded to fan control. See Fan 50 Plus.
gas pressure - LP gas pressure must be 11" of water column (6.25 oz per sq. in.), checking and adjusting requires a manometer.