Carrier logic board

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Carrier logic board

Postby Rsc12 » Wed Jul 27, 2011 8:20 am

I have a customer with Carrier 38ck042330 condenser with a logic board in it. The logic board controls the low voltage from the furnace and has T1, T2, T3 terminals on it. When there is a call for a/c the contactor clicks but does not pull in all the way to start the compresser or fan. My question is if the logic board is just a delay timer for the condenser and do i need it? Thanks for your help in advance. Sc
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- Carrier logic board

Postby nomadpeo » Thu Jul 28, 2011 6:07 am

what is the voltage reading at the contactor coil when it tries to pull in ?
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Postby Rsc12 » Thu Jul 28, 2011 8:12 am

2.4 - 1.4 - 25. When I disconnect the board and bring Y and C to the contactor every thing runs fine. I just don’t know what that board is for and if I need it or not. The wiring diagram describes it as factory optional part but not what it does.
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Postby nomadpeo » Thu Jul 28, 2011 10:59 pm

it sounds like a flaky time delay relay. no, it is not essential. however, if you have pressure cutout safety switches, you should pick up a time delay relay made by icm. it does not use a common and will have two terminals. wire it in series with the coil and the pressure switches. make sure it says 'delay on break' and set the time for the full 10 minutes. that way, if a safety opens, the control will force a 10 minute delay before retrying. this will prevent short cycling of the circuit when the pressure switch automatically resets. you should be able to pick this up in most ac supply houses.
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- Carrier logic board

Postby Rsc12 » Fri Jul 29, 2011 11:05 am

Thanks nomad. There is'nt any high or low pressure switches on this condenser. I have regular time solid state delays, but nothing like this board.
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Postby heatseeker » Fri Jul 29, 2011 11:39 am

I think nomad nailed it with the flaky timer.
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