3A Fuse Blowing

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  #1  
Old 07-07-13, 02:58 PM
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3A Fuse Blowing

My 3A fuse on my attic unit keeps blowing. After replacing it works for a few hours and does cool, then blows again.

- I have had an AC tech out twice and they checked the tstat and outside units for any shorts. They replaced the contactor outside. They said the next step is to replace the control board.

Anything else I can check? Its hot as hell here in Texas and I don't want to wait till mid day Monday before having another tech out to try something that may not even be the fix.

It seems the fuse lasts longer when its night / cool in the attic. It blows much quicker during the hotter parts of the day, leading me to believe its still something outside with the compressor.
 
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Old 07-07-13, 03:09 PM
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Welcome to the forums.

Since it happens intermittently it's going to be tough to find. If it seems to be heat related then maybe there is splice that has been taped together and is shorting when the tape gets soft and hot.

They can check all they want.....they won't find a short unless it's shorted at the time when they check for it. That would mean the best course of action is for you to visually check the control wiring......especially from the house to the compressor unit for breaks or places where it can short.

If you can't find a visual break then you may need to have the wiring replaced.
 
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Old 07-07-13, 04:26 PM
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Maybe ill get some new wiring while I am out since it wouldnt be that long of a run to just run it out of the attic and out of a window for a few days to test.

What gauge is typically used for the 2 conductor to the outside and the 5 conductor to the tstat?

...nevermind I found it appears to be 16 gauge. It sounds weird, but would speaker wire suffice for a few days? I know more weatherproof is ideal. Or maybe even multiple conductors of a cat5 ethernet cable? I have plenty of boxes of that laying around.
 
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Old 07-07-13, 09:39 PM
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NO, it should be 18 awg solid wire. Thermostat wire can be purchased at a home improvement store of your choice. If it is just 2 wire running temporarily.... then speaker wire will suffice (again, for temp only).
 
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