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Old 09-27-2019, 11:28 PM   #1
Junior Member
Brand: Thor Motor Coach
Model: Vegas 24.1
State: Montana
Posts: 23
THOR #16625
Power Converter Fan

So, Mother Nature has decided that winter is coming early to Montana. We are expecting snow and overnight lows in the 20s this weekend and into next week. I haven't winterized anything, as I wasn't expecting winter yet. We thought we might get one more small trip in before the season changed.

Due to the forecast temps, I plugged my Vegas in today and in order to turn on the tank heaters. I think I am being overcautious, but oh well. When I plugged it in, the fan on the bottom part of the power converter came on. That is the first time I have ever noticed that fan come on. I waited for a while to see if it went off, but it was still on after about 20 minutes.

Why is it on and should it eventually go off?

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Old 09-28-2019, 02:02 AM   #2
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16ACE27's Avatar
Brand: Thor Motor Coach
Model: ACE 27.1
State: Florida
Posts: 5,667
THOR #7035
It comes on when there is a "heavy" DC load. Heavy in my coach can be anything more than float charging the batteries. So if I have all my lights on at night the fan runs until bedtime.

Ted & Melinda
2016 ACE 27.1
2016 Chevy Sonic Toad
2020 Chevy Colorado Z71 Trail Runner Alternate Toad
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Old 09-28-2019, 02:45 AM   #3
Senior Member
Brand: Keystone
Model: Sprinter
State: Florida
Posts: 1,319
THOR #15553
Your tank heaters are 12 volts. That and a low battery will cause the fan to run. it runs while it is charging the battery.
2011 Keystone Sprinter 323BHS. Retired Master Electrician. All Motor Homes are RV's. All RV's are not Motor Homes.
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Old 09-28-2019, 06:13 PM   #4
Junior Member
Brand: Thor Motor Coach
Model: Vegas 24.1
State: Montana
Posts: 23
THOR #16625
I think part of my confusion was that there was no load. The fan was on before I turned the tank heaters on and nothing else was turned on. The fan was off when I went back out last night. Good to learn new stuff.

A question for clarification: do the tank heaters just have an on/off or do they have a thermostat where they only apply heat when the temperature gets cold enough? I know I have to switch them on. I am talking about actually heating.
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Old 09-28-2019, 06:39 PM   #5
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Brand: Thor Motor Coach
Model: 2018 24.1 AXISSIXxSIX
State: Arizona
Posts: 3,130
THOR #13932
My fan always comes on at start up of electrical system on, but only great occasion thereafter.

My heater pads click on below I think 35°+-.

Turn yours on.
Feel them for heat.
This is a sure fire way to tell


In case yours aren't thermostatically controlled, the link is an easy solution that provides valuable information.

(one of these is going in my fridge vent in case it gets too hot in there. Probably unneeded, but 8 bucks, 12v already available in the vent, and the handful of old computer fans I have is a reason to do it.)
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