Central Airconditioning unit (Electrical Question)

Old 06-14-03, 05:25 PM
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Central Airconditioning unit (Electrical Question)

My question concernts hooking up the electrical on my central air unit.

I opened up the unit outside..and have three wires green, red and black.

The green goes to ground..and it looks like the red and black are for power.

Where is the White Common wire?

I bought this house..and it was wired this way.
The black and Red go to a terminal that is attached to the house....then the red and black wire connects to white and Black wire...leads into the house.
Then they led the white to common and the black to power.
I was under the understanding you are to use 220...so would need two power wires.

Knowing that there are only three wires coming out of the outside unit, does this mean a common isn't needed?
Help if you can..thanks
Old 06-14-03, 06:57 PM
Ed G
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Typically on residential units they are 220 volt. So you would have 2 black wires from the circuit breaker to the disconnect at the unit. This ussually has fuses but not always. Themn you have two wires from the disconect to the line side of the contactor. Some times these wires are black others can be red ort even blue. White should never be anything except nuetral, never power, but, things happen. If you have a meter check the voltage at the disconect.
Old 06-14-03, 07:42 PM
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Turns out they shouldve connected the white to the other side of power on the breaker. But, they forgot to tape the white wire for power. They also used the copper as common....
Thanks for the help.
Old 06-15-03, 10:34 AM
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Just make sure you have both legs to the A/C unit so you have 220 at it and not 110 ED

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