12 volt Ceiling fan switch is hot

[Indian Creeker]

We have a 2012 Salem 393FKDS Park Trailer. We have 12 volt ceiling fans in the bedroom and also in the living room area. Each is on a different circuit. The fan in the living room started shutting itself off. I'm not an electrician but I do small repairs, as most handy men, when I can.
I started investigating the problem. I removed the switch from the wall and found that as the fan ran, the switch became hotter to the touch, until the fan shut itself off. (This switch is the brains of the fan. On/off, forward/reverse, with speed control.) I ordered a new switch from Forest River and replaced it. The new switch does the same thing. Where do I go from here. For now, we are not using the fan. We have no problems with the bedroom fan. Thanks for any suggestions you can give me.

Dave

[carl.net]

Check all your connections from the battery to the switch. If any are lose or corroded you may have extra resistance which causes heat. Also the motor may either have issues or need to be cleaned. Try blowing the motor out. and cleaning the fan blades.

[Hob]

Just my humble opinion but I would tend to lean toward a bad motor in the fan.

[Nigels]

Obviously not the switch then, would it be a big job to swap the fans over, if its just 4 screws and a couple of connectors swap them over and see if the other switch heats up.

Whilst the motors are out you could check continuity and resistance (I,m not a spark but it sounds good) perhaps someone with experience can chime in here in how to test and what to look for.

[Indian Creeker]

Not a bad idea, if Carls idea doesn't do it, I'll probably do just that, Thanks
Dave

[Iggy]

The motors and switch may be getting warm because....

If your battery voltage is low and are not charged to 12.6 Volts plus you will obviously get a lower voltage such as lets say 11 volts when all things are on.

This 11 volts is reduced by approx 10 % of what it should be.
Now if the voltage is reduced by 10% and the resistance is the same. (the fan motor) then the amperage will increase in equal proportion by plus 10%

so now your 12 volt fanis running on 11 volts
lets say it tales 1 amp to run at 12 volts and now it will be 1.1 amps at 11 volts.
This is just an example so yours may actually be different.

This lower voltage and higher amperage will create heat in wires, switches and motors.

So to help you need to check your battery fluid levels.
With a multimeter check battery voltage with nothing running and no charger. Disconnect shore power will do this.

Then turn things back on without shore power and see what the battery voltage is.

I suspect you will find a weak cell or two in your battery.

Oh if you are interested in my theory you can search by looking up Ohms Law on the web.
E = I x R Voltage (E) = current (I) times resistance (R)

[Indian Creeker]

Thanks for the suggestions, Iggy, this all makes sense to me, but I still have the second identical fan in the bedroom that doesn't have any problems. So, am I missing something that I should be getting?

[oldprof1]

Your not missing anything. However reduced voltage to a motor will NOT cause the current to rise the same percentage. It's more like 30% increase. Critical motor voltage is 10% below rated voltage, at this point further reduction will cause the motor to burn out from overcurrent. Motors are voltage sensitive devices.

I would suggest you measure the voltage at the switch and at the motor of both units while the motors are running. Compare the values. If the voltage is low at either unit, presumably the hot one, try to trace the lost voltage in connections from the battery to the switch to the motor.
Cheers and good luck

[MillerTime]

A lot of motors have thermostat switches to shut down if temps get to high (like a bearing starting to go out). When the motor cools it will allow the motor to start again. Also a bearing going out wilk increase friction and increase load which may cause a swich to get hot. If this is the case a continuity or resistance test will turn nothing up because it is mechanical not electrical. If the motor stops you can test this by appying compressed air to cool down motor and see if it resets quicker than it was before (such as a couple min instead if 30).

Just my 2 pennys

[Herk7769]

My 2 copper colored zinc coin input has more to do with how the switch reduces voltage to the fan. If your switch uses a high wattage resistor to reduce the voltage (instead of a solid state device), using any setting other than high will result in a "hot switch" and may be perfectly normal.

Low voltage will cause that resistor to consume more current and thus create more heat. Too low a voltage and a slow speed setting can cause enough heat to damage the switch (and possibly the camper).