help needed wiring new central air fan


  #1  
Old 07-31-09, 01:35 PM
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help needed wiring new central air fan

Hello all, I've got a 25 year old a/c unit for my house. Recently it quit working, and I had an a/c guy who was a friend of a friend diagnose it, and said it had a bad fan....

I picked up a new fan off ebay that seems to be an exact match, except for the wiring.

The old unit has a black wire, a brown wire and a blue wire.

It also has a dual capacitor on it.

the new fan came with a capacitor, so I understand that the brown and brown/white wire will to to the new capacitor they gave me.

however, I'm not sure what to do with the yellow wire.

I'd guess that the black wire goes to the hot side, but what do I do with the yellow wire?? I was reading up, and do I understand the yellow and black wire go to the same post?

do I just twist the yellow and black wire onto the hot side?
 
  #2  
Old 07-31-09, 01:49 PM
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Is this the fan on the outside compresser unit?

Are there nameplates on the motors? When you say they seem to be an exact match, what do you base that on? Need to verify the fan speed, horsepower, etc.
Doug
 
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Old 07-31-09, 02:02 PM
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This one is a universal motor, though the dimensions are the same....1/6 hp on both, both 1075 rpm's.

the old is a ge 5kcp39bg and the new is a reversable ao smith fse1016sv1


I just verified the old wiring, and the blue and brown wire go to a terminal on the old dual capacitor, and the only other wire, the black one goes to the hot side of that switch in the a/c unit.

SO, the brown wires are to the NEW capacitor, then black still goes to the same black terminal, but what to do with the yellow?? does it go to the black side too, or the red side??

thanks!

btw, sorry, yes it's the fan on the ouside compressor unit
 
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Old 07-31-09, 03:02 PM
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Here is the AO Smith manual with wiring diagrams. You'll need to paw through them to see which one applies to your motor. http://www.aosmithmotors.com/pdf/brochures/_2294.pdf

I'm surprised there isn't a wiring diagram on your motor.
Doug
 
  #5  
Old 07-31-09, 03:42 PM
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yeah there should be a diagram on the motor. The old motor was wired to the C and F terminals on the dual cap, right? blue to C and brown to F? Take you multimeter, on the new motor brown/white stripe should show continuity to either black or yellow [probably yellow] WITHOUT any resistance. In other words- either brown/white stripe and black are wired together internally or brown/white stripe and yellow are wired together internally. What you're not understanding is the motor is 240 volts which means it needs 2 hot legs in order to operate. One hot leg is at the contactor [where black from the old motor went] the other hot leg is at the C terminal on the dual capacitor. Whichever wire on the new motor shows continuity with brown/white stripe goes to C on the dual cap, the other one goes to where the black used to on the contactor and the 2 browns go to the new cap. You will not be reusing the F terminal on the dual cap. Look for the wiring label on the new motor to verify.
 
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Old 07-31-09, 04:25 PM
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Thank you so so much!!!

It now comes on and works, and a/c blows cold!!!

Bad news is, the old fan was SO rusted on, that I tweaked it pulling it off, now the entire unit shakes BAD. Guess I've got to find a new fan now
 
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Old 07-31-09, 06:32 PM
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Thanks for the feedback. Do you mean the fan blade? get that fixed or it will wipe out the bearings in the new motor.
 
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Old 08-01-09, 01:18 AM
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yea, the fanblade is warped now...I even tried putting it on a table, and put a level across the top, it's bent.

I've got a local shop I'm calling tomorrow...if not I'll get one online. I won't run the a/c till I get that swapped out.

Man, that old fan was seized onto the old shaft. No amount of prying and hammering would get it off. I finally had to cut the shaft off the old motor with a hacksaw, then use a punch to drive out the rest of the shaft from the fan...by that time, it had seen too much abuse.
 
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Old 08-01-09, 05:08 AM
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They can be a bear. It's important that the new fan blade has the same blade pitch [iow- the number of degress of angle of the curveature of the blade wings]. The pitch is often stamped on the hub or one of the blade wing arms. Usually the number is 22 to 33 degress with about 24 to 29 being the most common. The concave side of the wings scoops the air, that's how you'll determine rotation.
 
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Old 08-04-09, 02:13 PM
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Final update...I found a wonderful place, AAA electric out in riverside ca that deals with electric motors, fans, and pumps. Huge place, and amazing prices.

They matched up my fan with a new one and I headed home and installed it.

Not a single vibration..SMOOOOOTH.

My house is cool, I'm not sweating any longer, and I'm not so grumpy.

In this economy, nothing beats a DIY repair. Thanks so much for all the help!
 
  #11  
Old 08-04-09, 04:27 PM
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Thanks for the feedback.

jjjjjjjjjjjjjj
 
 

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