Blown Fuse - Safe to replace?


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Old 07-02-07, 08:30 PM
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Blown Fuse - Safe to replace?

Hi,

My Central heating and cooling system stopped working a few days ago. The thermostat is still responding and attempting to turn the system on and off. After checking the breakers, I went up into the attic and found a blown 15 amp type T fuse where the attic unit plugs in.

What would cause this to blow? I there anything I should check before replacing it?

Thanks!
 
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Old 07-02-07, 10:28 PM
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Wink

For sure try another fuse. Can be the blower motor up there or its capacitor. Dont get why the tstat still works. Most of the time the 24V transformer power is in there and it would be dead also.
 
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Old 07-02-07, 11:22 PM
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used the multimeter to check for continuity, if you hear the beep sound, then the fuse good vice versa.
 
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Old 07-03-07, 02:32 PM
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Update- Changed the blown fuse and everything powered right up. I wonder why it blew in the first place?

The thermostat has 2 AA batteries in it so maybe that's why they continued to operate.

Thanks!
 
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Old 07-03-07, 05:50 PM
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Update 2- OK I'm back at square one. The fuse blew again.

Can anyone suggest what I can check?
 
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Old 07-04-07, 04:47 AM
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Is the fuse blown or burned? Could you tell it was blown by looking at it? If so, the issue is heat from a bad connection. Can sometimes be cleaned and tightened.
 
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Old 07-04-07, 11:30 AM
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Wink

Check the blower motor and its capacitor.
 
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Old 07-05-07, 07:18 PM
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Thanks for the reply.

What is the best way to test the motor and capacitor? Are there tests I can perform with my multimeter?

I opened the blower housing, it's very clean and spins without much resistance.

After I replaced the fuse (again) it seems like the volume of air is lower than I remember.

Any ideas?
 
 

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