I have Carrier residential furnace with control board HH84AA009. The unit does not turn on at all. I have checked the thermostat and it is OK. The 24V transformer puts out 24v. I suspect the control board is shot but there is no way to confirm. Before purchasing a new control board I wanted to check to see if there was a way to confirm the failure. Could there be anything else that's preventing the ignition process to kick-in?

Thanks in advance for the help

You need to make sure you do not have any other 24 volt circuits that are open. Limit controls etc.

Here is a direct replacement board wiring diagram to help you.

http://www.icmcontrols.com/downloads/icm275_ag.pdf

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Originally Posted by HenryD

I have Carrier residential furnace with control board HH84AA009. The unit does not turn on at all. I have checked the thermostat and it is OK. The 24V transformer puts out 24v. I suspect the control board is shot but there is no way to confirm. Before purchasing a new control board I wanted to check to see if there was a way to confirm the failure. Could there be anything else that's preventing the ignition process to kick-in?

Thanks in advance for the help

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I will check on the other circuits and let you know. Thanks for the wiring diagram.

HenryD, some of your limit switches may be manual reset , they will have a small button between the wires of the switch. Good luck, Mike

That's the board for the older 80% furnace that had three wires going to the pilot assembly. You may have a bad pilot assembly. If the inducer board was bad the pilot would light and then go out. If you had 24 volts at sec1 and sec2 on the main furnace control board and had any open limits the blower would be running all the time. If you can turn your thermostat fan switch to on and the blower works its not a bad blower. The pilot assembly can get stuck open and nothing will work on the heat side.

Also check the fuse.

If the low voltage fuse is blown the blower runs all the time but you have no heat or a/c.