Furnace thermostat has no power


  #1  
Old 07-06-13, 07:35 AM
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Furnace thermostat has no power

Hi,

I am new to the forum but dealt with furnace issues before. I have old Payne furnace in the house that recently purchased. When we inspected the house the furnace was working, but after closing the thermostat had no power (it was old anyway without backup batter). So I thought thermostat went bad and replaced it with a new one and that didn't help. Then I checked furnace itself I am only able to turn the blower fan with the switch. I read that there might be some fuse that could get blown, but I don't see any fuses on the circuit board. What can I do? Any suggestions appreciated.

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  #2  
Old 07-06-13, 08:17 AM
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On the bottom edge of the circuit board are 4 terminals. They should be marked R, W, Y, & C. Make sure you depress any door switch present & check for 24 volts AC between R & C. If no voltage is present & there is no fuse, you could have a bad control transformer.
 
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Old 07-06-13, 09:48 PM
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Looks like there is no power in those connectors. I will try replacing control transformer, it doesn't look too expensive
 
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Old 07-07-13, 07:24 AM
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Before throwing parts at it, make sure you have 120 volts to the transformer. If you do, check the output side for 24-28 volts. 120 in & nothing out = bad transformer.
 
 

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