Carrier furnace


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Old 12-11-18, 02:32 PM
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Carrier furnace

My thermostat controller is completely dead. I checked on the electrical that supply the furnace and is good. Opened up the furnace cover and found out the PCB board unit is CEPL 130438-01. I checked on the AC electrical input to the DC power converter input and no power. I replaced the PCB board and still dead. Is there anything else that may go wrong. Thanks
 
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Old 12-11-18, 02:35 PM
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Welcome to the forums.

That board doesn't run on 120vAC..... it only switches that voltage to the blowers and igniter.
The board runs on 24Vac. Look for a 120vAC to 24vAC transformer. That's what probably is defective.
 
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Old 12-11-18, 03:04 PM
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Yes it's. But I think the 120vAC that run to the DC converter come from the PCBoard and does not have the 120VAC to supply the converter. I assume there is another sensor to give signal a relay to power up the DC converter. thanks
 
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Old 12-11-18, 03:08 PM
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Maybe I need to check on the PCB itself (including the newly bought unit). How to test this board?
 
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Old 12-12-18, 11:03 AM
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The PCB is Ok, I tried it on another unit and it works.
 
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Old 12-12-18, 01:32 PM
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These boards run the 24vac from the transformer through a limit switch and flame rollout sensor. If either is tripped/broken then the board will act dead like you are seeing.
 
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Old 12-12-18, 01:37 PM
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Can you tell me which one is the limit switch and Flame rollout sensor ? Thanks
 
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Old 12-12-18, 02:39 PM
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I found the flame roll out sensor. checked and reset it and still dead.
 
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Old 12-12-18, 02:56 PM
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Are these two different sensors ?
 
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Old 12-12-18, 06:00 PM
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What is the model number of your furnace?
Follow the wires. Roll-out switch just above burners. Limit switch can be above or below but is to sense temp in air going through system. Sometimes in blower compartment.
 
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Old 12-14-18, 07:39 AM
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Carrier model: PG8JAA066110
 
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Old 12-14-18, 08:24 AM
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I found the limit switches as well . There are two limit swictches on the heat exchange and another one on the flue elbow. Including the Rollout swicth there are 4 sensors chain in a series connection.
 
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Old 12-14-18, 12:36 PM
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Diagram on page 32 - https://www.questargas.com/ForEmploy...G8M%20PG8J.pdf
First check for 24vac at both sides of the fuse. Then at each of the roll-out sensors and limit switches.
 
 

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