NEED HELP... !! Electric side of water heater heater keeps blowing buss fuse

[hidefman]

Alright need some help here... I own a 2010 keystone Laredo 303tg .. I can’t seem to figure out why when I turn my water heater on for the electric side of it .the switch in the camper (not the one on the outside of the heater) . it blows a blue 15 amp buss fuse .. same one every time.. the one it keeps blowing controls the carbon monoxide detector, water pump switch , and whatever else is on the same circuit...haven’t figured out yet what’s all on that circuit .. but when I replace the fuse and leave the electric side off and try to use the lp gas switch .. it ignites and heats just fine... already pulled converter out and checked wires , pulled the heating element and checked and tested that ( comes up with 10.4 ohm) , pulled the cover off by reset buttons on outside and the wires there appear to be fine , pulled the switch panel off the wall and those wires looked fine from what I could see without pulling the wall apart... the only thing I haven’t done is pull the belly down to check the wires up there yet

Any help figuring this problem out would be GREATLY APPRECIATED!!!! Thanks in advance

[Frank G]

You should have a Atwood water heater and they do have a 12VDC control circuit. It is a quick look up on the internet. From what you describe there is a short in the wiring from the switch to the WH or a shorted relay on the WH. If you disconnect the white wire on the WH you can isolate the problem from the wiring or the unit.

The heating unit is 110VAC

Hope this helps

http://www.atwoodmobile.com/manuals/...S%204.9.09.pdf

[hidefman]

Originally Posted by Frank G

You should have a Atwood water heater and they do have a 12VDC control circuit. It is a quick look up on the internet. From what you describe there is a short in the wiring from the switch to the WH or a shorted relay on the WH. If you disconnect the white wire on the WH you can isolate the problem from the wiring or the unit.

The heating unit is 110VAC

Hope this helps

http://www.atwoodmobile.com/manuals/...S%204.9.09.pdf

I just looked and its a suburban brand

[hidefman]

And this is the converter I have , already shut the power to the electric side of it off .... and the fuse that’s the bright blue is the bay it keeps blowing..

[Frank G]

Here are the instructions for the suburban SW6D.

http://waterheatertimer.org/pdf/Subu...ice_Manual.pdf

It is confusing to me why you are blowing the 12 volt fuse when turning on the electric heating element. Your Ohm reading is a little off as it should be 14.5 to 17 Ohms. You could disconnect the heater element and see if the fuse blows, but why is a 110 VAC circuit taking out a 12 VDC fuse??? On the suburban unit the 12 VDC is only used for the Direct spark ignition.

OK, will the unit heat water on electric with the 12 Volt fuse blown? If it does the electric side is intact and working.

Does the Gas side work with the electric side turned off?

Did everything work last time you used the unit?

[hidefman]

We bought the unit last October.. when he was showing us it it worked then...

Yes The gas side works when the electric is off ..
no it won’t heat water on the electric side with fuse blown ...
And here’s my switch setup

[hidefman]

And yes it blows it with the element disconnected

[sourdough]

Looks like it is a relatively simple AC circuit. It comes from your switch in the house (when turned on) to the switch on the WH through the thermostat then the heating element....that's it. Turn the switch off at the WH and the one inside on. Make sure the fuse doesn't blow. If it does there is something else on the circuit causing the problem. If nothing happens disconnect feed connection (incoming) to the element (2nd component in line) to isolate the thermostat; turn on the switch at the WH. If it blows then turn off the switch (WH) and disconnect the feed lead to the thermostat (1st component in line). Turn the switch back on; hopefully it doesn't blow and it would indicate the thermostat. Of course what fails, and where, is anyone's guess but that might at least isolate it to something. Good luck.

[hankpage]

Have you looked inside the junction boxes behind or next to the WH. These boxes sometimes share high and low voltage connections. I would suspect a melted or loose connection shorting in the junction box. If insulation is burned, your nose may help you find the right junction box. JM2¢, Hank

[hidefman]

Thanks for the input,, but I’ve already tried with the switch off on the outside of the unit , I’ve even went as far as having the power to the unit itself from breaker side off with the switch on the outside off as well at the same time, ..

I tried even tracking where the wires went from that circuit... I know the fridge is also on it.. turned that on and doesn’t blow the buss fuse.. so I’m thinking it’s gotta be something from the switch to the unit itself..

That’s gonna be my next step probably is pull the unit out and Check the junction boxes... I can only get at one of them .. the other is buried behind the other side.. ugh ☹️

[chuckster57]

I bet there isn't enough slack in the romex to pull the WH out. You have to be a contortionist to access the junction box, ask me how I know LOL!!!

[hidefman]

Originally Posted by chuckster57

I bet there isn't enough slack in the romex to pull the WH out. You have to be a contortionist to access the junction box, ask me how I know LOL!!!

U say you’ve done it before... what do I have to do to get it out..??? Just remove the trim ring and cut some caulk or am I missing something... thanks

[chuckster57]

Look at my sig...I'm an RV tech, so yeah I've done it a couple of times LOL!!!!

You need to get to the backside of the water heater to access the 110 junction box and often times the 12V wiring also. When they build these tings they don't leave much slack in the wiring. I don't really see a need to remove the water heater.

[hidefman]

I can get to the 110v side easily enough but I can’t get to the other junction box that squished between the wall and the unit itself...

Didn’t realize you were a tech .. so my bad..

Here’s the 110 side junction box.. the other I can’t get to and that’s the switch side of it.. looks like there’s enough slick just to pull the unit out far enough to get at the other box

[chuckster57]

The 12V is the control board. It will unplug from the harness and the igniter for testing.

[hidefman]

Originally Posted by chuckster57

The 12V is the control board. It will unplug from the harness and the igniter for testing.

Now does that control board run just the gas side or both gas and electric??? ...

Then how would I go about testing that board... thanks in advance

[chuckster57]

You would need to get a tester or take it to an RV repair facility that has the tester. Its not a cheap piece of equipment so DIY is about out of the question. If you can get a decent wiring diagram for YOUR model it will show any common wires. I think the grounds are shared.

[hidefman]

Originally Posted by chuckster57

You would need to get a tester or take it to an RV repair facility that has the tester. Its not a cheap piece of equipment so DIY is about out of the question. If you can get a decent wiring diagram for YOUR model it will show any common wires. I think the grounds are shared.

I’ve got a Continuity / ohm tester with digital display would that work?

[chuckster57]

Nope, not for the control board. Here is a wiring diagram...Look at the relay

https://www.bing.com/images/search?v...x=0&ajaxhist=0

Located in the 110 junction box. I'm leaning towards that.

[sourdough]

I think I misunderstood the issue. I agree with Chuckster.

Had to replace the control board on my Atwood about 3 months ago - $223.