Water heater not working & other 12v issues

[median]

A few days ago we started having issues with the 12V systems in our Skyline Nomad 278 trailer. The lights would flicker, the refrigerator light would go off and the water heater wouldn't come on (Atwood G6A-8E). Interestingly enough, by early afternoon the issues with the lights and refrigerator would stop and start again sometime after we've gone to bed.

We've been running solely on shore power for about 18 months with no issues until now, and all 110V outlets are working fine.

All breakers and fuses were / are good. I replaced the 12V power supply, swapping the 35A stock PSU with a 50A, thinking maybe it was failing and not delivering enough current, but the problems continued.

Having downloaded and followed the Dometic Water Heater service manual and followed the troubleshooting guidelines, I discovered that there is no voltage at the wall switch (manual specifies 10.6V and above). Continuity across the switch is good.

I checked the fuses again with my multimeter on continuity and while there is no fuse marked 'Water Heater', none of the fuses are blown.

A little stuck as to where to look next. My thinking is that the 12V should go from the fuse board straight to the wall switch, but does it? And where does the ground come from (it says from the water heater so maybe a ground problem)? Also, which dang fuse is the water heater on in the first place?

Any suggestions as to where to look next would be appreciated. Thanks in advance

 

[median]

Also, does anyone see a problem with taking the 12V from the water pump switch (we don't need the water pump) and diverting it to the water heater switch?

Thanks

 

[CharlesinGA]

No two RV's are wired the same. Check for power on both sides of the fuses. I assume you have power at the 12v fuse panel. Power runs from the fuse to the switch and back to the water heater.

Also, does anyone see a problem with taking the 12V from the water pump switch (we don't need the water pump) and diverting it to the water heater switch?

I would try that as an experiment, but if it fixes it, I'd keep searching for why you don't have power on the proper switch.

Charles

 

[median]

Thanks, Charles.

There's power at the 12V fuse panel and all 12V systems are powered aside from the water heater.

 

[Rene T]

I would unplug all the wires on the circuit board and clean them using a pencil eraser.Do this one at a time. Once cleaned, plug them in and unplug them several times to clean the mating contact.

Oh, and welcome to the forum. If we do help you, please let us know.

 

[median]

Thanks Rene.

All the wires connect to the circuit board via screw terminals. All screws are tight.

 

[Martian]

Have you checked the water in your battery?

 

[median]

We've been running without batteries for over 5 years since they died.

 

[uchu]

The power converter might be acting up.

 

[CharlesinGA]

You really do need a battery, even if only one small deep cycle. The converter does produce DC power OK but the battery helps smooth out the voltage. The "power supply" (properly known as a converter) can experience Alternating Current ripples that find their way into the DC output side and cause devices and equipment to act up. This is probably due to electronic components failing.

Charles

 

[Kirk]

The lights would flicker, the refrigerator light would go off and the water heater wouldn't come on (Atwood G6A-8E). Interestingly enough, by early afternoon the issues with the lights and refrigerator would stop and start again sometime after we've gone to bed.

Since the problem shows in the lights, the refrigerator. and the water heater, why are you only looking at the water heater? Those items all get power from the 12V system so your problem very unlikely to be in the water heater. Have you monitored the voltage of the 12V system when the problem is taking place? It sounds like that voltage is changing.

Also, does anyone see a problem with taking the 12V from the water pump switch (we don't need the water pump) and diverting it to the water heater switch?

That just depends on your skill level but if the issue is the 12V supply, that isn't going to change anything.

 

[LarsMac]

12 Volt DC water heater?
I can't imagine that being terribly efficient.

 

[Gary RV_Wizard]

I agree that a small 12v battery would be a plus for smooth & uninterrupted power, but don't think that's the issue here. Especially with the new converter, which which will have much better power regulation than the original.

As Kirk says, this problem seems broader than just the water heater. The fridge & lighting also show the symptoms, even if intermittent. Power isn't reliably moving thru the 12v distribution panel.

But to answer your specific question, yes you can use an alternate 12v circuit as the source. The 12v is used only to power the heater's circuit board, so power demand (amperage) is tiny.

 

[Domo]

Thanks Rene.

All the wires connect to the circuit board via screw terminals. All screws are tight.

All connections are capable of developing corrosion on the contact surfaces, whether slip-on, plug-in or screw.

@Rene T 's good suggestion is in hopes that ALL contact surfaces have been removed, cleaned and re-assembled.


Here's what I do when troubleshooting anything electrical on our MH and I'm sure I've saved myself from future issues by performing some of these steps as preventive maintenance as I troubleshoot.

1. Bring CRC contact cleaner and lubricant, meter and crimpers with you when troubleshooting.
2. Remove all the related plugs and screw terminals from their sockets, spray both plug and socket with CRC and then insert+remove about three times to help break any corrosion.
3. Remove fuses or relays/breakers from sockets and dowse their contacts and sockets with CRC.
4. Look for crimp-on connections and re-crimp them (or replace if you see green/oxidation of the wire).
5. Trace all ground wires to the ground block or chassis. Remove them, scrape any dirt or paint off, clean the contact and bolts and put it all together. If those grounds are simply fastened with self-tapping screws, remove the screws - scrape the paint and use a bolt to secure the new connection.

You may also apply dielectric grease to contacts to help shield against corrosion. Use it springly as a little goes a long way.

Hoping this helps you, if not for today's issue, then for some in the future.

 

[Utclmjmpr]

The water heater he specced is a gas heater so only a tiny amount of current is needed to ignite it and continue running. It could be a grounding problem also..>>>Dan

 

[8Muddypaws]

My first thought was a grounding issue.

Are you sure the converter is getting consistent power? Rv's are notorious for loosening connections inside the AC breaker panel. Especially the neutral (white) wires because they often put multiple wires on the same lug. Tighten all of them anyway. I mean really really tight.

Be sure to unplug your trailer from outside power and turn off any inverters or generators you might have before opening that breaker panel.

 

[CharlesinGA]

12 Volt DC water heater?
I can't imagine that being terribly efficient.

Its a gas only water heater with 12v DC control circuit and spark ignition.

Charles

 

[John From Detroit]

You said lights are flickering. Do you have a volt meter (5-10 bucks at harbor freight is good enough but mine,,, A bit more expensive as they do more) make sure you have about 13-14 volts.

Another very useful tool is an automotive test light. (same Harbor freight) this looks like an old fashion ice pick with a test lead coming out the handle.

Every RVer needs these tools for electrical trouble shooting.

 

[Kirk]

My first thought was a grounding issue.

For that to be the case, it would be a ground that is common to all of the affected lights and appliances. That is possible, but highly unlikely.

 

[median]

Thanks for all of the great information. You guys rock!

i took the 12V wire from the water pump switch and metered it against the ground of the water heater switch. I got exact 12V. Unfortunately, connecting that to the heater switch did nothing. Not even turning on the lamp in the switch.

I double checked continuity across the water heater switch so that's not an issue. Really rather confused why an alternate 12V supply isn't working.

I don't think it's a ground issue on the water heater switch as the pump 12V read correctly using it.

Any other suggestions would be most welcome.