3a fuse blown, nothing comes on, diagram/pic below


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Old 07-08-12, 01:26 PM
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3a fuse blown, nothing comes on, diagram/pic below

A 3amp fuse has blown twice in the last few days. I replace and unit has run only to break again. I found one neutral white wire that seemed loose, but suspect that was not the root cause.
The fuse is inline b/t a 24amp converter and a large pronged plug w/ about 8 wires. I don't know how this works or what could be causing the fuse to blow. The filter is clean. Perhaps coils need a cleaning as it's been a while, but not sure if dirty coils would cause this result anyway.
Thank you V MUCH in advance for any tech support. feel free to ask questions.
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Old 07-08-12, 01:33 PM
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Old 07-08-12, 01:39 PM
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I was able to inspect that control wire from the outside unit all the way to the indoor unit and found no cuts/breaks or other trauma.
 
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Old 07-08-12, 01:42 PM
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You can try fan only. If the fuse does not pop it would point the the wires between the house and condenser.

Can you check inside of the outdoor unit for shorts?



Do you have an Ohm meter?
I believe that I usually measure about 12 ohms at contactor and reversing valve coils.

I have seen 3 ohms pop the low voltage fuse that you are speaking of.
 
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Old 07-08-12, 01:58 PM
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Ok. I do have a meter and believe i can ck the outdoor unit as you suggest. However, I'm not sure what you mean by "reversing valve coils". btw, the unit has been running (full AC/compressor/fan) since about 8am this morning... so???

Assuming there is no short as you suggest, what would be the next target? Thx again, i'll be back on later. You're very generous to provide the help.
 
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Old 07-08-12, 02:03 PM
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A reversing valve is found only on heat pumps.



Intermittant shorts can be tough to find. I would check for wires rubbing against the hot gas line inside of the outdoor unit. Especially pressure switch wires.



 
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Old 07-08-12, 02:08 PM
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Ok, will check these wires late tonight or in the morning. thank u. love how u have all these pre-canned answers to facilitate your assistance.
 
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Old 07-08-12, 02:19 PM
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Pictures sure make helping people much easier.

 
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Old 08-17-12, 09:45 AM
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My unit continues to blow the 3a fuze periodically. A few days ago, it would instantly blow a replaced fuze (only when AC is on, not when just fan runs). I followed the low voltage line on both ends and it appears well connected, no trauma to the line, no apparent shorts.
I am not sure what the previous person meant about measuring ohms at reversing valve coils. I do have a meter, but not sure what to test. Any new suggestions?
Filter is clean, but i have not cleaned the inside coils in a number of years. Could this be an issue?
thank you so much for your help. trying to resolve so i don't have to spend on wkend HVAC help!
 
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Old 08-17-12, 12:49 PM
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Fixed. As orig suggested, low voltage line from the indoor unit to the outdoor unit was compromised. i did not find it the first time b/c the wire had been chewed thru inside the double thick brick wall that it goes thru to get outside. i could not see this portion of the wire on my original check. but 2nd try i pulled it thru and could see a small animal had chewed on it within my wall cavity. thank you Houston!
 
 

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