‘Revving’ sound at night

[LABluebike]

Still getting used to the 2021 GT. Hearing a strange ‘revving’ sound at night. Actually looked out the window to see if a car was revving it’s engine, but no. Last night, in order to sleep, I finally pressed the Battery Disconnect to ‘Store’ and the sound stopped immediately. (Hooked up to shore power 30; AGMs, factory 180 solar.) The sound is coming from above about midship.
Thanks if you have any ideas!

[Dan and Liz]

Do you leave the water pump switch on?

[OTRA15]

Ditto

[BayouBiker]

Perhaps it's the refrigerator coil fan....

[grumblin]

From above? Is the FV open a tad?

[Dlongworth]

Do you have a satellite dish?

[JCWDCW]

My first guess was the the cooling fan in the converter. It stopped when it was no longer loaded and had to charge the batteries. However it may also be the cooling fan in the refrigerator chimney. Don't know why it stopped when you disconnected the batteries???
JCW

[DKB_SATX]

Since this is a new-to-you unit, and the sound went away when you hit the battery disconnect, I think your converter-charger was dumping a lot of charge into the batteries and got hot, and was running its internal fan at full speed. It may also be that the converter-charger has a problem and was running the fan unnecessarily, but when you dumped the battery-charging load things got quiet, so that's a place to start.

How long had you been plugged in when this happened? While AGMs are tough, they're not indestructible... it may be worth having them tested. Since you were plugged into shore power, the only difference the store/use switch should make is whether or not you're charging the batteries, all your internal 12v would keep working as before, making some of the other trouble-shooting steps less likely to be applicable.

[solomon.m]

Might also have a look at the fridge. In my 2020 FC the fridge has a cooling fan that makes a revving sound coping with 110+ outdoor temps. It has a thermal sensor that shuts the fan off when temps stabilize. I know the 2021 versus 2020 have different fridges, but still may be the source

[LABluebike]

Just got back from the trip. We were in cool weather on the California coast, so my guess is that it is probably the converter charger cooling fan while all charged up. It definitely sounded like a struggling fan.
Yes, also thought of the refrigerator, but it is not on the Battery Disconnect circuit, so the new GT ‘fridge is probably not the culprit.
We had the water pump off at the time. On the second night (after my OP) I tried turning the water pump ON, and it seemed to go away again. (But not sure as it was morning and ambient sounds were getting higher.)
Next trip will dry camping, so if it persists, that should narrow things down!
Thanks so much, my AS friends.

[Al and Missy]

Originally Posted by LABluebike

Just got back from the trip. We were in cool weather on the California coast, so my guess is that it is probably the converter charger cooling fan while all charged up. It definitely sounded like a struggling fan.
Yes, also thought of the refrigerator, but it is not on the Battery Disconnect circuit, so the new GT ‘fridge is probably not the culprit.
We had the water pump off at the time. On the second night (after my OP) I tried turning the water pump ON, and it seemed to go away again. (But not sure as it was morning and ambient sounds were getting higher.)
Next trip will dry camping, so if it persists, that should narrow things down!
Thanks so much, my AS friends.

1. The converter is usually under the sofa or the bed. Unlikely you would think it was coming from above.

2. Why do you say the fridge is not on the Battery Disconnect circuit? Most things that run from 12 volts are and the fan would be one of those. Does your fridge run from Propane? If it does the control circuits run from 12 volts - even when hooked up to and operating from shore power.

I'm betting on the fridge fan.

Edit - According to AS website, the fridge runs from 120VAC shore power or 12V (batteries), no propane. It will run from batteries when there is no shore power (but not very long). I don't know how the switching is accomplished. It could be just wired to the batteries and runs off of the converter when shore power is available.

I'm still betting on the fridge fan.

[Hiho Silver]

Do you have a surge protector mounted inside your trailer? When I did it made an
annoying noise, but I would describe it as more of a hum.

[LABluebike]

Thanks again for the new ideas. (Surge protector is exterior.) (Fridge still runs in ‘Store’ mode, hence my comment it being off that circuit.)
The upcoming dry camping trip should help eliminate some possibilities!

[Orondo]

Can’t help but weigh in on a mystery. If the ‘21 GT has a tankless HW heater then that might be the culprit. Our whole house tankless Rinai heaters would often make a whirring noise even when there was no “demand” for hot water. Problem solved with a check valve / timer - as any change in water pressure caused the heaters to cycle. Not sure how the new tankless system in the new AS works as we have the “old” 2016 28 Signature .

[kpfate]

I have a similar issue/question as we just returned from a 3 day trip (2nd outing with our 2018 22FB Sport) and once we got back to the house and plugged her into home power...about an hour or so later there was a "hummmmm" coming from the refrigerator. It is a 3-way that runs on propane, gas or battery and we had it running on propane beginning 2 days before we left. Got nice and chilled without question, but the "hummm" has me concerned.

We are new at this and are learning each time we go out so any info would be great!

Thanks in advance!

:0)

[DKB_SATX]

Originally Posted by LABluebike

Thanks again for the new ideas. (Surge protector is exterior.) (Fridge still runs in ‘Store’ mode, hence my comment it being off that circuit.)
The upcoming dry camping trip should help eliminate some possibilities!

When you're plugged into shore power, the only thing the store/use switch does is stop the batteries from charging. The converter-charger supplies 12v for everything else, and your fridge most likely runs off the 120v input at that point . To test what is and isn't disconnected by the store/use switch, you need to first unplug from shore power, THEN switch to "Store." Most likely it'll just be your propane detector and the jack, though I've heard some trailers have the subwoofer bypassing the disconnect switch as well.

[DKB_SATX]

Originally Posted by Al and Missy

Edit - According to AS website, the fridge runs from 120VAC shore power or 12V (batteries), no propane. It will run from batteries when there is no shore power (but not very long). I don't know how the switching is accomplished. It could be just wired to the batteries and runs off of the converter when shore power is available.

I'm still betting on the fridge fan.

I'm pretty sure the all-electric 2-way is a 12v/120v Danfoss compressor fridge, so it'll probably run about 24 hours on battery without charging. It's WAY more efficient than the ammonia absorption fridges and probably doesn't require an external vent at all, much less the vent van.

[Al and Missy]

Can I change my bet? If the USE/STORE switch just disconnects the batteries, then the noise almost has to be the converter fan, as others have suggested.

[OTRA15]

Originally Posted by LABluebike

Thanks again for the new ideas. (Surge protector is exterior.) (Fridge still runs in ‘Store’ mode, hence my comment it being off that circuit.)
The upcoming dry camping trip should help eliminate some possibilities!

Looking forward to your updates later, for your 2020 25' Globetrotter.

Happy trails,

[Bruce B]

Originally Posted by DKB_SATX

I'm pretty sure the all-electric 2-way is a 12v/120v Danfoss compressor fridge, so it'll probably run about 24 hours on battery without charging. It's WAY more efficient than the ammonia absorption fridges and probably doesn't require an external vent at all, much less the vent van.

Compressor type refrigerators must have cool air to work. Many of the issues people have aboard boats that use Danfoss type compressor refrigerators involve sufficient air flow. A friend of mine had a new fridge that could not hold temp this summer, he was annoyed because the refrigerator was acting exactly like the one he replaced... we removed the unit and cut holes in the cabinet to help the poor thing breath. Problem fixed!
It went from running almost 100% of the time to about 40 minutes an hour and the box temp dropped a good 10°.