# hvac fan



## frodo (May 29, 2015)

hello guys,  i have a hvac central unit fan  i took out of an old unit

which wire is the hot and common?

i have red,blue,yellow white black

i thought it was white black,,i was wrong

want to put it in the shop,,to keep cool with


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## nealtw (May 29, 2015)

I can tell you that trial and error does not work, I tried with one a few years ago, it ran for about ten minutes bfore it broke into flames.


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## frodo (May 29, 2015)

yeah,,,,,,i touched wh blk  to a cord and it said errrrrrrrrrrrrrrrrr...so i stopped to ask directions


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## bud16415 (May 29, 2015)

There is supposed to be a rotary switch to go along with your fan I think. The blue red and black will go to the switch. I think white would be common and yellow power. The switch would make connections for speeds. 
That&#8217;s just my guess without really digging into it.


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## frodo (May 29, 2015)

bud16415 said:


> There is supposed to be a rotary switch to go along with your fan I think. The blue red and black will go to the switch. I think white would be common and yellow power. The switch would make connections for speeds.
> That&#8217;s just my guess without really digging into it.



i got it

white- common
blk-  high speed
blue- medium
red--low speed

yellow, some kinda safety bs


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## bud16415 (May 29, 2015)

Again I&#8217;m just guessing but I think it&#8217;s a two speed fan. Switching between blue and red or blue and black maybe to get a high and low speed. Power to yellow and white to common??????
Are there any identification markings on it? If you get an idea of how it might be wired you could connect those wires and then measure resistance to get a clue. 

Or wait around till a pro sees your post and get a good answer. I wouldn&#8217;t just start throwing power to wires though. Good way to burn something out.


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## frodo (May 30, 2015)

still,working on it.

i have blue abnd white to a pig tail  fan is running

but.

what is the yellow?

i found a generic wire diagram,,but it has a purple where i have a white




motor nomenlature


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## frodo (Jun 14, 2015)

put a pair of wire cutters and a screwdriver in my pocket
walked around the junk yard..founda old fan, motor gone but switch still their

got the 3 speed switch,  and wired it

it was easy,,,blk to blk, blue to,bl,,,red to rd

white to white,  grey to grey  green to scrw

works great..


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## falconbrother (Jun 28, 2015)

I replaced the motor in my air handler this winter.  Came home from the Caribbean too 22 degrees and no heat..  Anyway, there was a label on the old motor and the replacement motor that laid out where all the wires go and/or what they do.   Glad you got it running.  Good idea.


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