Tank heater lights not working

[kcsimms]

Hi all!
I own a 3760 FL. This morning all three tank heater lights worked. Later in the morning I looked and all 3 lights won't illuminate. We full time and it was about 27 degrees this morning. All the fuses are fine, including the ones for the level up system since we were told they are on the same circuit. I am out of ideas. HELP!!

Thanks, Kevin

[RMcNeal]

When I purchased our 2019 3791RD, I was told that the blue lights in the switches would come on when the heating pad was actually on. They are thermostatically controlled and go off when the ambient temp is high enough to not be concerned about freezing. If memory serves, somewhere around 50 degrees. I've had others on the forum say that was incorrect. I have not confirmed this either way, so it may not be correct.
If you have a clamp on meter, I suppose you could check the wires on the switches to see if there is any current draw on them.

[kcsimms]

Up until now the blue lights go on when I switch them on. The outside temperature is irrelevant. Plus it's 28 degrees outside right now. I can't figure it out?????

[RMcNeal]

It's hard to believe the led's in all three went out simultaneously.
Can you check voltage at the switch with a meter? They should be getting 12v power to light up.

[Daryles]

Your furnace will help with keeping them warm. Behind your basement walls there will be 1 vent hose that points down into the tanks void space.
If your freshwater tank is at the back (like mine) the furnace won't help if you have any water in it.
Maybe pull your control panel and see if there is any inline fuses back there. Check for 12vdc on the heater switches.

[rohrmann]

I wonder if the furnace heat going into the area where the tanks are is making it warm enough that the tank heaters won't come on. Maybe this morning it was colder where the tanks are, and as it warmed up a little along with the furnace heat, the heating pads won't come on.

[Daryles]

No, the lights come on with the switch on.
Its 65⁰F here in Virginia Beach.
The tank heaters do have a built-in thermostat.
On at 45⁰F off at 65⁰F.
I wish the thermostat temperature was on at 35⁰ off at 40⁰. It would save some batteries when boondocking at cold temperatures.

[kcsimms]

It's strange that all my blue lights went off at the same time. Took off control panel and no in line fuses. Checked all connections i could see and all look fine.

[Daryles]

I had the same problem
https://m.facebook.com/groups/274058...5987047458365/
I got lucky it was an inline fuse in the battery compartment.

[Carl n Susan]

Originally Posted by Daryles

I had the same problem
https://m.facebook.com/groups/274058...5987047458365/
I got lucky it was an inline fuse in the battery compartment.

Unfortunately, the FB link takes you to the main page where you can ask to join the group (even if you are already a member of the FB Group).



Can you cut/paste the info from FB to here?

[Daryles]

You already checked that fuse in Shellby's Montana RV Owners Group posts.
I had that problem back in January.
Search Keystone Montana RV Owners Group (FB)
Daryles Simpson January 9th 2021.
"Holding tank heater fuse?"

[kcsimms]

Yea, I checked all the fuses in the battery compartment and they were all good.

[Carl n Susan]

For those of you who detest Facebook or who, like me, find it difficult to find anything posted in the past, here is what I think was posted by Daryles. It only took about an hour to locate on FB (and folks say the MOC is difficult to navigate).

There is a red 5A fuse in the the battery compartment in the upper right hand corner. Make sure it is pushed in all the way. My heaters quit too. Found the fuse backed out. Pushed it in all the way and everything was working again. The fuse also runs the LCI level up control panel.

[Daryles]

Lol, thanks Carl ��

[kcsimms]

Thanks, I checked that fuse and it's good and snapped in. I'm lost but I don't want to take it in to the shop where they do more harm than good.

[Daryles]

In the files section there is the Keystone Montana "12 vdc wire standard Keystone rv.pdf"
The heater wires are tan and white according to this chart.
https://www.montanaowners.com/forums...?do=file&id=39
Maybe take down the basement walls and look for the wiring going to the Black and forward grey tank. Trace it back.

[kcsimms]

I think I'll try that. Thanks Daryles!

[bcrvman]

Originally Posted by kcsimms

I think I'll try that. Thanks Daryles!

Did you meter the back of the switches to see if there is voltage?

[kcsimms]

Yes, it turned out to be an in line fuse. Thanks everyone for the help!!!!

[Daryles]

Where did you find it?