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Airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 7517
Experience:  Furnace, A/C and heat pump specialist.
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I have a Carrier 58cma105 oil furnace. The blower doesnt

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I have a Carrier 58cma105 oil furnace. The blower doesn't shut off.
Hello. My name is XXXXX XXXXX I'll do my best to help. Troubleshooting often requires meters and test equipment. Let's get started and see what we can do.
If everything is working normally other than the blower just does not shut down, you have a bad control board. The fan relay is integrated into the control board which tells the blower to run or to shut down.The little black box built onto the board is the fan relay. Often you can gently tap those little black boxes and relay will unstick, bu will ultimately stick again and board will have to be replaced.
Customer: replied 2 years ago.

The whole board would need to be replaced? Can you just replace the relay?



On this particular furnace the relay is built into the board and can not be replaced independently.
Here is a link to the board. The small black boxes you see on the board are the fan relays.
Customer: replied 2 years ago.

Just one more thought... I was reading something about how it could be a "limit switch." Any thoughts on that?

That is why I mentioned "If everything else is working normally". If it is an open limit, the burners will not light. Are you having other issues besides just motor staying on?
Customer: replied 2 years ago.

Yes, the burners must be lit because the heat does kick on.


Thanks for your help. I just wanted to be sure I eliminated everything before replacing the board.

I understand. This is a pretty common issue with these boards. Feel free to follow up and let me know.
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