Original message
| D-lux
 |  "Help! control board fuse blowing"
, posted Wed 20 Aug 12:18  
th e 3amp fuse on my board keeps blowing only when the ac comes on ..the heat works fine and the fan works fine but as soon as i switch it to ac the fuse blows. i need to know where to start looking for problems?
thanks
ps goodman gmt090-3a furnace
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Replies:
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| sinead26ohara
| "Re(1):Help! control board fuse blowing" , posted Wed 3 Sep 21:04
Replace the outdoor contactors. As silly as that sounds, when the contact points become corroded and pitted they will not close properly causing an amperage spike on the low-voltage side, which in turn blows the control fuse on the air handler control board.
Sinead O'Hara
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| NATEDOG
| "Re(1):Help! control board fuse blowing" , posted Wed 20 Aug 12:54:
there probably is a short in the low voltage wires either in the outside unit or the 2 wire going to it.
[this message was edited by NATEDOG on Wed 20 Aug 12:55] |
| | yuri
| "Re(2):Help! control board fuse blowing" , posted Wed 20 Aug 15:13
Wire to outdoor unit got hit by weedwhacker, chewed by dog or rodents or deteriorated from sun. Happens all the time.
Yuri
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| | D-lux
| "Re(3):Help! control board fuse blowing" , posted Thu 21 Aug 12:02:
the wires all look fine if we are talking about the wire from the tstat that goes out side.Am i suppose to be getting voltage in that wire?could the transformer be doing it?how do i check the transformer?contactor? I can close it manually and the fan comes on
thanks guys
[this message was edited by D-lux on Thu 21 Aug 12:24] |
| | yuri
| "Re(4):Help! control board fuse blowing" , posted Thu 21 Aug 15:44
Disconnect the outdoor wire inside the furnace temporarily (label it first or take a picture or both). Then try start the A/C. If it blows then the problem is somewhere in the furnace or wiring from the tstat to the furnace. If not then your outdoor unit may have a bad contactor coil or short somewhere.
Yuri
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| | D-lux
| "Re(5):Help! control board fuse blowing" , posted Fri 22 Aug 09:51
thanks for all your ideas.ill try that this weekend but if its seems to be outside how can i check the contactor?
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| | yuri
| "Re(6):Help! control board fuse blowing" , posted Fri 22 Aug 16:00:
Not easily. As a tech I would get a new one from my truck and try it. Yours may drawing too much amperage. 99% of the time it is a wiring short.
Yuri
[this message was edited by yuri on Fri 22 Aug 16:00] |
| | D-lux
| "Re(7):Help! control board fuse blowing" , posted Mon 25 Aug 15:31
it was the coil on the contactor only measured .5 ohms across theterminal that go to the coil and i called a heating place and they said it should be around 12 ohms. replaced it for 19 dolars and it fired right up.
thank you for all your help saved me money that i didn't have,
thanks
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