Range Hood Light causes Breaker Box fan to run

[Brantleycmd]

Hello,
First time posting here! I recently bought a 2020 NoBo 19.8 and came across something a little weird (but maybe totally normal). Yesterday while camping I heard a fan revving up and down sporadically. No rhythm to it, it would just go into high RPMs and low RPMs seemingly at random.

At first I couldn't figure out where it was coming from, but quickly realized it was the cooling fan inside the breaker box. Up until this point, I had never heard that fan once despite spending a good deal of time in the camper with power on the week after purchasing it. I checked all the breakers and fuses, and visual inspection of the fan checked good.

Spent far too long going over it, then my wife came in and turned the range hood light off. The fan stopped immediately. I turned it back on, the fan started back up. So it is clearly tied to that.

This may be a long post for someone to just come in and say "that's normal", but I want to be sure it's not a symptom of something else like overdraw or a short somewhere.

Thanks in advance!

Edited to add: this was at night, with only that light on. Not even the AC running. I turned the hood light on since it was a softer light to find something without waking the family.

[kenandterry]

Do you get the same fan activation by turning ON any other 12 volt accessories?

Other lights throughout the rig? Factory ceiling fans?

[NMWildcat]

Your converter is usually part of the 'breaker box' or directly behind the power panel.
If you are plugged into shore power, the converter will charge your battery and help supply 12v to your 12v RV system.
While it is doing so, it is normal for its cooling fan to cycle on and off.

[Brantleycmd]

Originally Posted by kenandterry

Do you get the same fan activation by turning ON any other 12 volt accessories?

Other lights throughout the rig? Factory ceiling fans?

Nope. That’s what made me ask. I know the purpose of the fan, it’s just odd that it’s IMMEDIATE. Light on, fan on. Light off, fan off. If it’s going off a temp sensor you’d think it would still be hot for a little bit after turning off, and take a little bit to warm up when turning on. But it’s acting almost as if the fan is tied to the switch.

[Brantleycmd]

Originally Posted by NMWildcat

Your converter is usually part of the 'breaker box' or directly behind the power panel.
If you are plugged into shore power, the converter will charge your battery and help supply 12v to your 12v RV system.
While it is doing so, it is normal for its cooling fan to cycle on and off.

Yes. But it seems abnormal that it would do so based on one specific light being turned on or off. It’s immediate. Acting as if the fan were controlled by the range light switch. Doesn’t seem normal to me. Especially given it was only that light, and the fridge, on at the time. AC was off, it was the middle of the night, no other lights or appliances running.

[DES-1]

We've had similar experiences in out former 19.7 where the converter fan turns on for a seemly insignificant current draw. Nothing to worry about, and you know the solution. If I'm not mistaken our hood did the same thing in our 19.7 and I believe the hood had an old style incandescent bulb.

[TacomaJoe]

The light in my fan was incandescent and I changed it to LED. I'm thinking that your converter fan is triggered by current rather than temperature and that fan light pulls enough to trigger it.

[NMWildcat]

Originally Posted by Brantleycmd

Yes. But it seems abnormal that it would do so based on one specific light being turned on or off. It’s immediate. Acting as if the fan were controlled by the range light switch. Doesn’t seem normal to me. Especially given it was only that light, and the fridge, on at the time. AC was off, it was the middle of the night, no other lights or appliances running.

I understand. There might not have been anything else on, but the converter was still charging the battery, as well as powering all the parasitic draws. Was your battery perhaps pulling the charger into bulk mode?
I have noticed my fan operates a lot more when the ambient temperature is higher, than when it is cold. I also have a set of LED ceiling lights that will always cause the fan to come on, although it will turn off occasionally.
If you are still concerned, replace the light or fixture, or both, and see if it changes anything.

[Larry-NC]

Originally Posted by TacomaJoe

The light in my fan was incandescent and I changed it to LED. I'm thinking that your converter fan is triggered by current rather than temperature and that fan light pulls enough to trigger it.

You seem to be correct. This is perfectly normal.

I have three lights on the same switch in the Cherokee 38P. After I replaced the LEDs with brighter LEDs (more current), I could trigger the converter fan on and off with the light switch. It doesn't take very much. Similar thing in the other trailer. I'm guessing 5-10 amps total is enough to do it.

[Sbosserman]

Originally Posted by TacomaJoe

The light in my fan was incandescent and I changed it to LED. I'm thinking that your converter fan is triggered by current rather than temperature and that fan light pulls enough to trigger it.

I changed my incandescent (halogen) bulb over to LED because it was too dim, but also because it got so hot that it melted the light lens! Now the light is bright white and no more hot bulbs. I used these T10 led lights from Amazon:

https://a.co/d/a21vDyT

And these wire pigtails:

https://a.co/d/8hhdxU0

Then I just clipped off the current bulb pigtail, wired on the new pigtail and used double sided tape to stick the LED bulb to the old bulb mounting area. I also had to order a new plastic light lens for $17 dam dollars which is ridiculous!
But it works soooo much better now.

[jimmoore13]

Originally Posted by Sbosserman

I changed my incandescent (halogen) bulb over to LED because it was too dim, but also because it got so hot that it melted the light lens! Now the light is bright white and no more hot bulbs. I used these T10 led lights from Amazon:

https://a.co/d/a21vDyT

And these wire pigtails:

https://a.co/d/8hhdxU0

Then I just clipped off the current bulb pigtail, wired on the new pigtail and used double sided tape to stick the LED bulb to the old bulb mounting area. I also had to order a new plastic light lens for $17 dam dollars which is ridiculous!
But it works soooo much better now.

I think you've hit on the "problem." While almost every light in a current rig is LED, my range hood has an "incandescent" bulb...perhaps halogen as yours was. The color temp is very "red" vs. the bright blue-white light from the rest of the fixtures. A typical incandescent bulb will draw roughly 4 times the amount of power per lumen output as compared to an LED.

Frankly, the light is a poor light as a work light...especially since the lighting around it is seemingly so much brighter due to the bluer color temp.

The OP's rig does not have a problem, but if boondocking, and if the range hood light is used a lot, it makes sense to change to an LED to reduce power consumption and have a brighter light in the bargain.

PS. My converter fan is also very sensitive to seemingly small loads, BUT since I boondock almost exclusively, when I fire up my generator to run, say, a 120 volt appliance like a coffee maker or the microwave, the converter fan will cycle on and off with even the slightest load...even a couple of LED lights. I attribute this mostly to the fact that the converter is simultaneously trying to charge the batteries...as well as support parasitic loads. Of course, if you start the microwave, the converter fan runs full tilt boogie until the micro shuts down.

[Larry-NC]

Originally Posted by jimmoore13

PS. My converter fan is also very sensitive to seemingly small loads, BUT since I boondock almost exclusively, when I fire up my generator to run, say, a 120 volt appliance like a coffee maker or the microwave, the converter fan will cycle on and off with even the slightest load...even a couple of LED lights. I attribute this mostly to the fact that the converter is simultaneously trying to charge the batteries...as well as support parasitic loads. Of course, if you start the microwave, the converter fan runs full tilt boogie until the micro shuts down.

This last sentence makes no sense at all. Why should running a 120Vac microwave affect the load (and fan) of the converter? Anxious to hear your explanation.

[Alde]

i would check your battery condition as well as the connections, if a cell is lower the battery requires more amps and the converter is trying to compensate