I have a 2000 Damon Daybreak 2960 that I am having issues with. The Roof Mounted Air Conditioner runs fine on the generator, but when connected to shore power it trips the breaker for AC. If I try to reset the breaker, I hear a loud humming noise coming from underneath the motorhome. The noise is coming from a box aprox. 1ft by 1ft by 5 inches. It has a huge fan in it - which reminds me of a "water wheel" sorta.I thought it could be the converter, but it looks like my converter and automatic transfer switch is contained at the breaker location under the bed in the back of the motorhome.I am at a loss what this box/fan could be that is making the loud hum and throwing the breaker. All outlets and lights continue to work as they should.

Your going to need an electricianSounds like somebody mounted an auto transformer in the shore line and put it under the MHNot a good place for electrical itemsIt might be something else, but you need an electrician to take a look at it and decideNot a mechanic

Describe the "shore power", 15 amp, 20 amp, 30 amp, or 50 amp?Exactly what breaker is tripping?

Box could be an inverter.Issue could be a poor connection on a neutral.

Box could be an inverter.Possibly transfer switch.Any markings on the box?Issue could be a poor connection on a neutral.

I've never seen a transfer switch underneath the RVNever seen one that square size either or with a FANNever seem an inverter underneath the RVdo you mean AC as in the 120v input shore power House breakeror A/C as in the 20amp breaker in the RV breaker panel, that is only for the A/C unitSomebody could make weird mods, but it seems unlikelyPSA/C is used for Air Conditioningand AC is used for POWERso a statement like yours, can be a real Puzzlerare you tripping the breaker in the RVor the one you are plugged into

Loud Noise then Breaker trips when running Airconditioner

MEXICOWANDERER
Explorer
Aug 17, 2016
A loud "humming" coming from a switched power supply? New to me. Not being sarcastic. I wonder how many tens of millions of dollars get eaten annually because rigs run around without instrumentation? Look ma. A car with no dashboard - just a steering wheel...
enblethen
Nomad
Aug 17, 2016
wa8yxm:
Is your transfer switch right next to your converter?
The transfer switch could be OP's noise!
GordonThree
Explorer
Aug 17, 2016
I think we lost the OP... Will this be another mystery for the cold case files?
mikestock
Explorer
Aug 17, 2016
My money is on a faulty, automatic transfer switch. It is in the genny position, by default with a magnetic switch activated by shore power presence. If you can open the box you may see and smell the result of a bad connection.
MEXICOWANDERER
Explorer
Aug 17, 2016
Too many newbies demand a "Push This And Pull That" instant gratification. I hope this does not add to that long list.
Nickkle
Explorer
Aug 17, 2016
enblethen wrote:
Box could be an inverter.
Possibly transfer switch.
Any markings on the box?
Issue could be a poor connection on a neutral.

I don't believe this is a inverter, as the motorhome did not come with an inverter. I believe it might be a transfer switch, but I am not sure. The motorhome is up north and I won't be able to get a picture until Friday at the earliest.

The A/C Breaker keeps tripping - even if the Air Conditioner is in the "Off" Position. Every time I flick the A/C Breaker, it makes the humming noise in this box. This box is not underneath in a bay, nor near the batteries. I have to get underneath the motorhome to see this box.
Nickkle
Explorer
Aug 17, 2016
MrWizard wrote:
I've never seen a transfer switch underneath the RV
Never seen one that square size either or with a FAN

Never seem an inverter underneath the RV

do you mean AC as in the 120v input shore power House breaker
or A/C as in the 20amp breaker in the RV breaker panel, that is only for the A/C unit

Somebody could make weird mods, but it seems unlikely

PS
A/C is used for Air Conditioning
and
AC is used for POWER

so a statement like yours, can be a real Puzzler

are you tripping the breaker in the RV
or the one you are plugged into

Tripping the A/C Breaker inside the motorhome that is only for the A/C Unit. A/C Doesn't have to be turned on for it to trip - it trips regardless. This unit doesn't have a inverter, that I know about atleast.
DrewE
Explorer II
Aug 17, 2016
Why would a transfer switch need a large squirrel cage fan?

It's a bit of a long shot, but I wonder if maybe it's a central vacuum system that happens to be on the same circuit as the air conditioner for some strange reason. It could also be some sort of a blower/air handler for the heating and cooling system, though that would be rather unusual for use with a standard RV roof-mount air conditioner.
Nickkle
Explorer
Aug 17, 2016
DrewE wrote:
Why would a transfer switch need a large squirrel cage fan?

It's a bit of a long shot, but I wonder if maybe it's a central vacuum system that happens to be on the same circuit as the air conditioner for some strange reason. It could also be some sort of a blower/air handler for the heating and cooling system, though that would be rather unusual for use with a standard RV roof-mount air conditioner.

Exactly my thoughts. I wish I would have thought about taking a photo of the box when I was up there this past weekend. There is no vacuum system, and i'm pretty sure it is not a blower/air handler.
MrWizard
Moderator
Aug 18, 2016
What puzzles me is the A/C works on generator power, so there is nothing major wrong with the A/C
But the breaker trips when turned on and this device hums thrums ?
So the a/c power is going through this device ? Or at least some sort power circuit is going through it?
It appears to be connected to the a/c?
Part of the a/c system ?

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