Shorted Low-Voltage Wire Out to A/C Unit


Old 07-05-13, 10:32 AM
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Shorted Low-Voltage Wire Out to A/C Unit

Been having some trouble with cooling lately. After some digging around, found out the low voltage fuse was blowing. Replaced the fuse (3 amps), but it keeps blowing when I set the thermostat to call for cooling. The fuse ONLY blows when I call for cooling.

Ohmed out the wiring and found out the low-voltage wiring going out to the AC unit is shorted somewhere. It's a three-wire bundle of red, green, and white that controls the contactor. The green and white are shorted together. Disconnected the wiring to the AC unit and the fuse no longer blows.

Now, I wonder... what are my options? I have no idea how I can run new wiring out to the AC unit. There are no back-up or alternate wire bundles for me to use either.

Can I use the green and white wire together as if they were one?

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Old 07-05-13, 01:52 PM
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You can use the green and white shorted together as one conductor and then use the red as the second wire. But with the white and green shorted together how do you know the red won't become shorted too.

Usually the problem is where it exits the building and connects to the compressor unit. Have you checked that area of the wiring ?
Old 07-05-13, 02:09 PM
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Thanks for the reply, PJmax. True, I don't know if the red wire will eventually become shorted too. I briefly inspected the wiring where it exited the house and didn't see any unusual. The wire bundle is encased in a metal-like tubing (what's this called?) and was a little hard to get to, but I will check again more closely tonight. Maybe some bugs got zapped?

Is it safe to assume the wiring through the house is pretty clean?

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