Electrical gremlins

[justinhscott]

Help please?

Got back from a road trip. Left the coach (2018 ACE 30.3) unplugged in the driveway for two days.

Found these things not working on 12V:
Fridge - checked with a meter - not getting 12V
Front of coach ceiling lights
Bathroom ceiling light
Bathroom vent fan

Lights work on 110V.

Everything else is working on 12V - water pump, drop down bunk, ceiling vent fan, stovetop vent fan, slides, ceiling lights in the bedroom.

Checked the logical fuses, they were fine.

Any ideas?

[wa8yxm]

Ah the old "Screw Loose"

A word of warning. Check not only 12 volt but 120 volt One of the breakers on my RV took 3 1/2 turns to tight.. the device it ran (Air Conditioner) worked after I tightened the loose screw.

Many Rver's have a few screws loose a #2 Square bit often helps.

[justinhscott]

I think I figured it out!

The wire coming out of the back of the fuse panel seemed to have a loose connection. I was trying to jam my multimeter probe into it and all the sudden I hear the fridge click on. This weekend’s project: make sure all the wires out of the fuse box are snug.

Thank you all for your ideas!

[SJ-Chris]

Try this....

Shore power unplugged.

Turn on your RV engine. With the engine running, the chassis alternator should be providing a large amount of voltage and amps to your batteries. Then see if those things that weren't working are now working. If they are, then it seems like there is an issue with your house batteries.

-Chris

[wa8yxm]

I too am guessing low battery
Fans will work on 12 volt or six (or less) just slower
Same with lights in fact I have a 12 volt light in my bath here in the apartment (Used to be in the RV's half-bath) runs on I think 9 volts might be 6
The Fridge will NOT work on 9 volts. Nor will the furnace.

[Bobbo]

Maybe your batteries are dead.

[justinhscott]

The 120 is not plugged in. I checked the “most likely” fuses but apparently I should check them all.

Ken, I’ll definitely look for another fuse panel. I don’t know what a “large r fuse” is. What’s it look like and where might I find it?

My fuse panel is right next to my 120 breaker panel and only has about 10 fuses.

Thank you both for the ideas!

[Beverley_Ken]

If your ceiling lights/fan (all 12v) work when you are plugged into shore power, it's possible that your coach battery switch was set to disconnect the batteries, that would explain the power 120 to coach converter to 12v lights/fan etc.
If the disconnect switch position doesn't change the other 12v issues, look for additional fuse panels and a large r fuse or 12v circuit breaker that protects them.
On our c-class there are 2 12v panels, different locations, for the house portion and another 3 for the Ford chassis.

Ken

[BFL13]

Please clarify whether "everything else" works on 12v means when not plugged into 120v.

If all 12v only works with 120v plugged in, the converter is doing the 12v work, and you have dead batts or an "open" between the batts and the DC panel.

If some 12v things work on battery but not all 12v things, then it is individual 12v fuses on the DC panel to check if those things are on the panel. Some 12v things like slides and jacks are direct to battery, not via panel, and can still work on battery even if the panel does not.

So we need the whole story to sort this out.