Atwood Furnace Issue

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butchiiii

Well-known member
Joined
Sep 8, 2014
Posts
347
Location
Los Angeles
Hi Everyone,
I seem to have a problem with my Atwood furnace. Last trip out the furnace would
not come on. There was nothing happening. No blower motor started, no sound of any
ignition. Nothing. On the same trip we needed to use the air conditioner and it worked
fine.  Don't know where to start my troublshooting. The thermostat is a Dometic single
zone LCD model which controls the AC and the furnace. There is no heat pump. The
furnace is a Atwood AFMD20 series unit see attached pic. 15K output.
Where so I start. Thanks for the help.
 

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Here's a link to furnace troubleshooting that Gary wrote., Go through that, and ask any more questions you need to ask.

http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf
 
Goat is right.  Since the ONLY common component is the thermostat, I would start my troubleshooting with the furnace itself.
 
So reading thru Gary's furnace guide I guess that I need to get a voltmeter to test various circuits.
Is there one that you guys recommend? Or should I get a multi meter? All suggestions are welcome.
Thanks
 
Many here get by with a $10 Harbor Freight multimeter. If you're the kinda person that has to have top dollar stuff, get a Fluke. Read the instructions, and understand a bit on how to use it if you are not familiar with them. Simple stuff, like read the voltage of a 9 volt battery, then checking the ohms of a paperclip, reading the voltage of the outlets in your house, etc. Ensure you are on the right scale before taking measurements, and an energized circuit will at minimum blow a fuse in your meter if set on the ohms scale. Try to have half an idea what the reading should be before testing. Like you know your house outlets should be about 120 volts AC, and 9 volt battery obviously should be about 9 volts DC.
 
An inexpensive multimeter like the HF models will tell you all you need to know. Neither precision nor accuracy is required for diagnosing RV power problems, whether 12vdc or 120vac.
 
I have an assortment of Volt meters ranging from FREE WITH PURCHASE at Harbor Freight to .. MSRP of around 250 dollars (I paid less got it at a "Fire Sale") and frankly. any of them work.

As someone said for RV use. other than battery State of harge. nethier accuracy nor precision is all that important...

Another handy tool (not for this job) is the Automotive TEST light.. HF sells those too

This looks like an old fashion ICE PICK but with a wire coming out of a plastic handle. a light bulb inside the handle

Just now My furnace is not working. however I know way. Forgot to turn the blanghed switch back on.
 
Gary & Johnic tool
Thank you for the advice. While I'm at HF is there any other diagnostic tools
that I should have to trouble shot problems in the trailer? Might as well get them
now and build my repair kit. TIA
 
Okay I finally got to go back to our TT to check out the furnace issue. We got to our destination
and I set up. Turned on the propane and 5 minutes later the furnace comes on and I can't turn it off.
The Dometic LCD single zone thermostat was in the off position at the time. I cycled to the heat setting and set the
temp way below the temp that it would call for heat but it still would not shut off. So I turned of the propane
and after failing to light it finally shut down.  Turned the propane back on and it stayed off until about
2am in the morning it came on by itself again with the thermostat in the off position and the inside temp
way above any need for heat being called.aWhat could possibly be the problem. Thermostat? I did not see anyththing
in Gary's trouble shooting guide that referenced this problem.
Help needed. TIA
 
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