Hi All,

I am attempting to replace the original control board (HK42FZ004) in my Payne heater with a new replacement board (Carrier 325878-751).

Unfortunately, there seems to be three wires connected on the old board that do not have obvious connection terminals on the new board. The wires are (as marked on the old board):

1) L2 – which goes to the main blower.

2) PR2 – which goes to a small iron transformer.

3) COM - which goes to one leg of the main AC line.

I do not see L2, PR2 or COM connection points on the new board. Does anyone know where these wires should be connected? Thanks in advance for your help! My email is barryabko (at) hotmail.com.

Thanks,

Barry

More detail: the actual part number for the new board is HK42FZ013.

Did this new board come with a wiring harness?

Hi Josh,

Thanks for your reply.

The first photo shows the old board (HK42FZ004) with the three wires attached in their original positions. L2, PR2 and COM wires are individual spade connectors. Where should they connect on the new board?



Did this new board come with a wiring harness?

Yes it did. Those are in use with the original harness blocks and are attached according to the instructions on the new board. Please see the second photo (the new board - Carrier 325878-751) and verify that I placed the two wires from the adapter harness in the correct positions. Both wires are now connected to "neutral" tabs on the new board.


Thanks,

Barry

Last time I did this board change had me stumped for a few as well. I think the L2 needs moved over on the top one space to the left as you can se the L2 marking. Also I would assume that the blw would stand for blower, so the botom one should be one pin to the right.

I would agree.

FWIW: EAC-2 means electronic Air cleaner. It's basically powered when the fan is runnig.

I have the same issue as this.

The OP stated that

1) L2 – which goes to the main blower.

2) PR2 – which goes to a small iron transformer.

3) COM - which goes to one leg of the main AC line.

Was there a specific set up?

Where does the PR2 connection goes... it goes to a small transformer?

Thanks in advance!

I just left the "com" out... the one that plugs into the small transformer and the board does not power on.

Any suggestions would be greatly appreciated. This is the same board HK42FZ013

This manual is for a unit that uses the same board. Pages 12 & 16 may be helpful. If you look closely at the neutral terminal cluster on the board, you will notice that "COM" is smaller than the others. This terminal is intended for the white blower motor lead.