All Trucks, Campers, Trailers, RV's and Motor Homes - Camper Furnace Help Please !

i have a 1996 Fleetwood Savannah fifth wheel camper. the furnace recently stopped working properly.the fan comes on but the unit does not ignite and produce heat.so far,from searching online,i have narrowed it down to the sail switch,limit switch,circuit board, or any combination there of. my question is...where is the limit switch located? it is a Atwood Excalibur 8500-III Series furnace.the two switches are inexpensive enough that i'm just gonna go ahead an replace them the start with. i cant find anything online that will show me the location of the limit switch and possibly the replacement procedures. any help is greatly appreciated !!!

You might repost this on the oil amd gas furnaces thread.

Any limit, operating, or fan disc type switch that has 2 wires can easily be checked for continuity with a volt-ohm meter set to ohms. if full continuity, it is good.

Does the fan just keep running and never shuts off, or does the fan only come on when the stat calls for heat?

And is the fan we are talking about the fan that blows out air into the camper for comfort?

Is the stat an on the heater?, or on the wall?, and does turning up the stat make the fan come on?, and if you turn down the stat does the fan shut off?

What kind of igntion does this have?

so far the fan just keeps running...i believe because its not reaching temperature an being told to shut off. i have not let it run longer than 4 or 5 minutes before manually turning the system off via the thermostat/control switch that is mounted on the interior wall.if i turn the switch from OFF to HEAT the fan comes on to purge the chamber before ignition attempt. the fan i'm referring to is the blower fan attached to the furnace.i have not tried lowering the the temperature to see if the fan would turn off on its own,i always end up turning switch from HEAT to OFF. the ignition system is DSI...direct spark ignition.

Mine acted about the same way and it was the "time delay relay" google "trouble shooting Atwood furnace" that is how I figured mine out. Part was about $30.

ok....thank you for the knowledge and info !!!

The easiest way to diagnose that is with a 12 volt DC test light, available at any hardware store or autoparts store for around $5.
Your high limit switch is way in back, usually very hard to see if you can see it at all from outside the vehicle where I assume your working from. Here's an easy test. Look where the 2 wires go into sail switch. One will be blue, the other will be white. Take test light and clamp ground to metal, on furnace somewhere easy & out of way. Now start furnace, and poke blue wire going to sail switch, test light should light up. If it does, now poke white wire, and it should light up as well, if not, sail switch no good. If light lights up on white as well, sail switch is good. Now, that white wire feeds 12 volts to high limit switch, way in the back, but the wire coming back from other side of high limit switch which is also white, should light up as well, and that wire is connected to the 4 wire connector on your ignition module/control. So if you poke the white wire going into the connector on module, and it has power, high limit switch is good, if not, high limit switch is faulty. Make sure you check the circuit breaker and switch for 12 + volts in and out, as in both wires attached to them both light up the test light. Here's a link to wiring schematic for reference. See page 5 of PDF file. Good Luck. Hope this helps. P.S. you can use a multimeter as well, I just find it easier with test light, and remember, get point in center of wire , up against something, and push hard enough to pierce into wire., but keep fingers back, and make sure your not close to fan/blower or anything that you may hit if it does slip when you push.

P.S. do you hear any clicking when furnace first starts up & starting to go through ignition phase? After fan/blower first starts, give it a few seconds and you should hear the clicking.You should hear a louder click, then a bunch of light clicks same time or right after louder one.

no,i dont hear it clicking as when its trying to ignite. thats the first thing i listen for. so far i'm gonna replace the limit switch and the sale switch mainly because they are inexpensive and fairly easy to replace.still not exactly sure where the limit switch is located,but i have a month or so before i'll actually be able to work on it again so i have time to search the whereabouts of it online. i would typically hear it click 3-5 times then the woooosh as the burner ignited. no clicks now,therefore no wooosh. lol

That's a fair amount of work, when a simple test with a multimeter or test light will tell you for sure, as well as the fact that replacing those 2 items, may not be your problem?
If you tell me the order & color of wires in the 4 wire connector on DSI board (control) , I can tell you what to check , real easy there, to see if it's a part malfunction, or the board.

it will be a few days before i get to the camper,but i will make a note of what the wire colors are and what order they are in. all i have is a 12V test light.i do not have a multi meter