DC fans reversed

[DocData3D]

I just realized today that the 12vDC fan for the stove hood and the bathroom vent are running backwards. These are the small cheap DC motors. However, the blower for the heater is running correctly.

I guess I can reverse the wiring but I'd sure like to know how this happened.

Thanks,
Dave

[et2]

I thought this was going to be a political thread.:B

[C_Schomer]

If some run right and some run wrong... it wouldn't hurt to check the battery hookup to be sure but just reverse the polarity on the motors that run the wrong direction. Flipping the blade doesn't reverse the flow! If the blades have a curve built into them, they won't flow nearly as much as when they are running correctly but the flow direction will be the same. Curved blades need to scoop the air just like a spoon scoops ice cream. Something like a fantastic fan has a twist in the blades but no curve or scoop cuz they are bidirectional... they need to blow equally in either direction. There are CW and CCW blades and that's what it takes to reverse the flow with a non-reversible motor... change to the other direction blade. Craig

[SCVJeff]

I'm not buying a line assembly person that does this all day long hasn't figured out the wiring protocol between house and RV. It's likely they have no clue other than what was taught them.
Where's the OP?

[Keith_Haw]

wa8yxm wrote:

bukhrn wrote:
Built on a Monday ? :@ Careless workmanship, poor quality control. 😞

I kind of agree with this but there is an even easier answer.

I'm cross trained. Certified Electronics technician, (Also an Engineering student) with Electrical training and experience though never certified or licensed in that field.

As an Electronics tech I'm used to black being Ground or Negative when working on automotive stuff.. Like that 12 volt fan.

But in HOUSE wiring black is HOT,, White is neutral (And in RV use will usually (NOT ALWAYS) be ground.

The idiot who built the think hooked the black wire to the black wire and the other wire to the other wire.. That simple.. NORMALLY that is how I would wire things too.. but if I'm working on 12 volt in a motor home.. I METER First.

Good answer, and that would be my guess to. But like has been said, I would check to make sure the whole unit 12v isn't wired backwards. Could be the main 12v supply wired backwards. After being in computers and electronics as long as I was, and a backyard mechanic/hot rodder, I sometimes have to think twice before I mess with house wiring.

[D_E_Bishop]

DocData3D wrote:
I just realized today that the 12vDC fan for the stove hood and the bathroom vent are running backwards. These are the small cheap DC motors. However, the blower for the heater is running correctly.

I guess I can reverse the wiring but I'd sure like to know how this happened.

Thanks,
Dave

Dave those cheap DC motors are over $40 to replace.

Dave

[pnichols]

Hmmmm .... maybe the OP's fans were wired up to run on conventional current instead of electron current. :h

P.S. Do RV batteries go longer between charges when supplying conventional current? If so, probably all of us should reverse our RV batteries and remount our RV fan blades upside down. :B

[Shadow_Catcher]

A multimeter is your friend, easy to test if current is reversed!

[SCVJeff]

Well the lights won't care what direction DC is going, but it's possible that the roof feeder is reversed. I would look at the lights and make sure they are correct before assuming that there were two mistakes made only on those polarity sensitive devices

[LindsayRichards]

He probably hooked them all up backwards and still is.

[wa8yxm]

bukhrn wrote:
Built on a Monday ? :@ Careless workmanship, poor quality control. 😞

I kind of agree with this but there is an even easier answer.

I'm cross trained. Certified Electronics technician, (Also an Engineering student) with Electrical training and experience though never certified or licensed in that field.

As an Electronics tech I'm used to black being Ground or Negative when working on automotive stuff.. Like that 12 volt fan.

But in HOUSE wiring black is HOT,, White is neutral (And in RV use will usually (NOT ALWAYS) be ground.

The idiot who built the think hooked the black wire to the black wire and the other wire to the other wire.. That simple.. NORMALLY that is how I would wire things too.. but if I'm working on 12 volt in a motor home.. I METER First.

[portscanner]

Maybe they put in a fan designed to be used in Australia. I understand that everything turns the opposite direction south of the equator.

[gbopp]

bukhrn wrote:
Built on a Monday ? :@ Careless workmanship, poor quality control. 😞

I think you're wrong. The quality inspector would have caught something that obvious during the detailed final inspection of the RV.
They don't miss a thing. :B

[Water-Bug]

Maybe the fan blades are installed upside down. 🙂

EDIT: 2oldman. You beat me by 30 seconds.

[2oldman]

Somebody put the fan blades on backwards?