Odd thermostat issue

[DQDick]

Our furnace has now started hitting the set temp and then no matter how cold it gets after that it usually doesn't start up again until I reset the thermostat and then it runs again. At times it will work normally for two or three cycles, other times only once. Dometic claimed to never have heard of this, but they are sending out a new thermostat. Since the furnace will sometimes work for a couple of cycles and then works again when the thermostat is reset, I can't come up with anything accept a bad stat. Any other ideas?

[jsb5717]

That's where I'd start as well. At least they're sending another one. Let's hope it does the trick.

[jimcol]

Dick, I believe you are on the right path and the thermostat replacement is what I would try first. But, (there is always a but), as you well know intermittent problems can be anywhere. Board, sail switch, limit switches? Looking forward to learning from your misfortune. See you in Nebraska.

[Chad R]

I had a similar problem with the AC side. I would set my thermostats and the AC would kick on and I could leave and come back later to find out the AC never kicked back on and it was really hot in the trailer.

I took the covers off, Used some canned air to dust out the board and some q-tips with alcohol to clean the interior board gently and so far both have been working fine since then. I found a ton of dust in them that might have been causing the problem with the temp sensor reading correctly

[DQDick]

On mine, when i reset it the thermostat knows the right temp, for instance this morning the termostat knew it was 67 when it was set for 73 but didn't turn the furnace on. The only other option I can come up with is there's a problem with the board locking out and I'm turning it back on after the 1hr lock out is over. I'll let you know what I find.

[DQDick]

Two clues developed before the mobile tech could show up. First I finally had a time when resetting the thermostat didn't work, but the furnace came on anyway about an hour later. Second, the cats started acting like there was a mouse in the basement and were looking thru the cold air return that's right next to the furnace. Based on the reset not always working and the Cat Scan we replaced the board with a Dinosaur board and all seems to be well now. Apparently the cats could hear something failing on the board because they since have had no interest.

[jsb5717]

Glad you got it fixed.

Maybe you could start a mobile "Cat Scan" business...

[DQDick]

[G & S Russell]

Does your new Cat Scan Co. need a consultant.

[G & S Russell]

Dick,
My 15 pound furry co-camper, Calvin is eminently qualified to assist in your “Cat Scan” venture. I thought my signature picture would show up on the post which shows Calvin sacked out in front of the fireplace, but I guess it didn’t, which made the last reply somewhat vague.

[DQDick]

Here are the boys, currently working on detecting where the furnace ducts are located.

[G & S Russell]

Dick,
Those are some hard working guys! How go you attach the picture to your message? I’m using quick reply and I don’t see the option. Thanks for you help.

[jsb5717]

Click on the Go Advanced button, scroll down to Manage attachments

[G & S Russell]

Jeff,
Thanks for the help. I see all the options now. I haven’t done much of this so I’m not feeling very confident. Practice makes perfect I guess. I am impressed how helpful everyone is.
Thanks again.

[G & S Russell]

Dick,
Here’s the picture I was trying to send as a resume for Calvin’s job application for your “Cat Scan” Company.

[DQDick]

Looks like he understands how to find heat so He's on the team.

[Byron B]

Dick, as we are presently in San Miguel de Allende for another month or so, and we regularly volunteer at the no kill animal shelter here, we will happily request that you send us any needs you have for your “cat scan” business. We have already fostered 6 different possible applicants this season and I can personally vouch for them and a few others that would make excellent employees.

[stevekbk]

a thermostat replacement is a2 part replacement.
1 thermostat
2 mother board
should be a warrantee issue.

[JamesD]

Is it a digital, or analog thermostat?
If it's analog, it has to be the thermostat, or the heater.
If it's digital, there could be a control board somewhere else in the system.
Mine has a control board in the main A/C on the roof, and I had to replace it.
I've also had to take out my furnace to clean out wasp nests, lint, and the jet.

[DQDick]

The problem has begun to return so I changed the resetable fuse and we'll see if that does the trick. If not the thermostat and control board are next on the list. Already have a spare thermostat so if we need to go further that will be next.