A/C Problems: circuit board issues


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Old 07-26-09, 12:42 PM
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A/C Problems: circuit board issues

A/C fan non stop:My furnace fan runs non-stop. Thermostat and outside unit is good, just the inside blower fan is running continuously. I think there is something wrong with the furnace circuit control board. When I pull the wire from the circuit board the fan is off. Does that mean there is a problem with the circuit board?(the circuit board cost $100 and is non refundable) The circuit board (P/N ceso 110018) is also not the same as the original model,the relay and most chips location is different but it said it can fit my A/C.

Please give me your input to troubleshoot this one.Beer 4U2

Thank You
 
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Old 07-26-09, 03:05 PM
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hmmm- is it a Carrier unit? I'm guessing that your furnace is gas? On many gas furnaces, if there is a problem with a limit control, the fans shifts to full time running. Can you post the model # and brand? Look on you existing board for G and C low voltage terminals. Turn off the thermostat and see if you have 24 volts from G to C. They should read 0 with the stat off.
 
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Old 07-26-09, 09:53 PM
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Smile

Mr Daddyjohn;
Thanks,
It is a Carrier unit,furnace is gas.
brand and model # :Carrier Corporation 518CXX036000MBAA

Turn off the thermostat and see if you have 24volts from
G to C. They should read 0 with the stat off.


Q: G to C your mean is test stat or furnace circuit control
board.
Q:If they read 0 with the stat off,that furnace circuit control
board means good or not?

I feel apologetic because I never fix A/C before,thank you
for your help !
 
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Old 07-27-09, 05:19 AM
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Test G to C at the board in the furnace. Don't forget to hold the little rocker switch for the furnace cover closed. If there is no voltage at G to C, you probably have a bad board. Are there any lights or readouts on the board? Is this a variable speed furnace?
 
 

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