Fuse Keeps Blowing in the Thermostat

[Fskoehl]

2019 Imagine 3170BH - went camping and used the furnace the first night with no issues...then on second night the fuse in the thermostat blew when I switch the unit to heat mode...replaced fuse and blew again...I took the rig to dealer and furnace worked fine...frustrating...apparently it may be a loose wire or something that is intermittent...anyone else had this problem? It has happened on several trips now and is aggravating...I don't want to jumper the little thermostat fuse without knowing more about what's going on...where would you look for loose wires or connection that may be causing this issue...why would it work fine one night and then not the next night? Then move rig and it works...ugghhhh!!
Rick

[howson]

2019 Imagine 3170BH - went camping and used the furnace the first night with no issues...then on second night the fuse in the thermostat blew when I switch the unit to heat mode...replaced fuse and blew again...I took the rig to dealer and furnace worked fine...frustrating...apparently it may be a loose wire or something that is intermittent...anyone else had this problem? It has happened on several trips now and is aggravating...I don't want to jumper the little thermostat fuse without knowing more about what's going on...where would you look for loose wires or connection that may be causing this issue...why would it work fine one night and then not the next night? Then move rig and it works...ugghhhh!!
Rick

Hello Fskoehl (Rick) and welcome to the forum. I moved your post to the "Electrical" channel. (Appliances would have worked, too, or HVAC.) I see this is your first post, so when you get a chance check out the welcome letter here: https://gdrvowners.com/forum/main-fo...to-new-members

Can you post a picture showing exactly which fuse is blowing, please? (I *assume* it's the 20A on circuit 5 but the drawing I'm looking at could be wrong.)

Howard

[Fskoehl]

Thanks Howard,
Actually the fuse is located within the little thermostat mounted on the wall...I pull the thermostat off the wall and there is a small round 2A fuse in the back of the Thermostat...I have ordered replacements before from Amazon...see below picture of what they look like...when I pull the blown fuse out and replace it, the thermostat will come back on and work until I change the setting to 'heat' and then within a couple seconds it just blows...
Rick

[Fskoehl]

Howard,
Here is the information on the fuse itself....
SIXQJZML 10 Pack F2AL Fast-Blow Fuse 2A 250V Glass Fuses 0.2 x 0.78 inch / 5 x 20 mm (2amp) (F2A)

[Country Campers]

https://gdrvowners.com/forum/operati...-blown-fuse-2x

Here is another thread and I think there is one more. Apparently there is an issue but I have yet to a resolution.

Brian

[Yoda]

2019 Imagine 3170BH - went camping and used the furnace the first night with no issues...then on second night the fuse in the thermostat blew when I switch the unit to heat mode...replaced fuse and blew again...I took the rig to dealer and furnace worked fine...frustrating...apparently it may be a loose wire or something that is intermittent...anyone else had this problem? It has happened on several trips now and is aggravating...I don't want to jumper the little thermostat fuse without knowing more about what's going on...where would you look for loose wires or connection that may be causing this issue...why would it work fine one night and then not the next night? Then move rig and it works...ugghhhh!!
Rick

Is there a way to access your furnace and the wiring connections ? In my thread on installing reverse back up lightning. https://gdrvowners.com/forum/operati...lights-install (first picture post #15) I found an issue on how GD ran the wiring along the side of my furnace at the lower back edge. the wiring bundel was in contact with the metal edging. I put the wires in a loom for protection. So take a look if you can.


Wires against sharp corner



Where the wiring bundle connected to furnace

Hope this helps
Keith.

[howson]

Howard,
Here is the information on the fuse itself....
SIXQJZML 10 Pack F2AL Fast-Blow Fuse 2A 250V Glass Fuses 0.2 x 0.78 inch / 5 x 20 mm (2amp) (F2A)

At this point I don't know if it makes any difference, but the GD Parts Lookup website (link on menu bar above) shows two thermostats used in your unit. It can be a BC7845 (9430-342) or a BB7841 (9430-338).

Which is in your trailer (or is it a different model)?


The 338's manual is available here (look for the link under the INSTRUCTIONS tab): https://www.rvupgradestore.com/Colem...-p/06-0705.htm

I can't find a specific manual for the 9430-342. (Frustrating!)

What I can see from looking at the manuals I could find is that power is consistently applied across the RED (+12v) and BLUE (-12vDC, or GND) wire inputs.



Do you have a multimeter and know how to use it?

[Fskoehl]

Howard,
I do have a multimeter and know how to use it...I will troubleshoot when I get back to Trailer...
Rick

[howson]

Howard,
I do have a multimeter and know how to use it...I will troubleshoot when I get back to Trailer...
Rick

Awesome. I agree with Keith ( Yoda ) that there's a wire between the thermostat and the furnace that's shorting to ground. It will take some troubleshooting to find it. Could be a staple shot through the thermostat wiring (has happened before) or as Keith shows wires chaffing against a metal chassis.

Not sure if it helps, but I think your furnace is an SF-35Q Airxcel (Suburban). Documents available here: https://techsupport.pdxrvwholesale.c...burban-sf-35q/

Can you tell if the thermostat wires go UP the wall or DOWN the wall to get over to the furnace? Curious if they are in the ceiling (hard to get to!) or above the coroplast to get over to the furnace. (Furnace, of course, is in the corner of the kitchen.

[Yoda]

Awesome. I agree with Keith ( Yoda ) that there's a wire between the thermostat and the furnace that's shorting to ground. It will take some troubleshooting to find it. Could be a staple shot through the thermostat wiring (has happened before) or as Keith shows wires chaffing against a metal chassis.

Not sure if it helps, but I think your furnace is an SF-35Q Airxcel (Suburban). Documents available here: https://techsupport.pdxrvwholesale.c...burban-sf-35q/

Can you tell if the thermostat wires go UP the wall or DOWN the wall to get over to the furnace? Curious if they are in the ceiling (hard to get to!) or above the coroplast to get over to the furnace. (Furnace, of course, is in the corner of the kitchen.

Howard - can he get to the furnace buy removing the drawers under the sink or stove? Just wondering. BTW Ill bet they went down and over to the furnace - that is what the did no mine. Just a thought.

[colan]

Couldn’t find the delete function, erased what was written, remembered after posting not applicable to this thermostat.