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Author Topic: ICP C9MPV - Fan Always On - Control Board Question  (Read 330 times)

Offline wantcoffee

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ICP C9MPV - Fan Always On - Control Board Question
« on: October 24, 2016, 09:08:22 AM »
Hi There,

The blower fan on my furnace is ON all the time. 

The thermostat is in AUTO, I have disconnected all the thermostat wires both at the thermostat end and at the furnace and it is still on, so I don't think its the wiring nor the thermostat.

I can get heat when heat is called, so I don't think its a limit switch.

I am thinking I have a stuck relay?!? I have tapped all the relays on boards and nothing changes.

So I am thinking I have a faulty board? 

What I am not sure is how to diagnose which board is the faulty one since there are 2 of them the ECM motor control board (ICP 1175594) and Furnace control board (ICP 1172809)

BTW, I verified the switch on my ECM motor control board was set on OFF for the fan, but whatever setting I put it in I can't get it to turn off, I am able to reduce the speed from high to low but thats about it.

Thanks in advance!


Offline Admin

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Re: ICP C9MPV - Fan Always On - Control Board Question
« Reply #1 on: October 24, 2016, 10:11:45 AM »
Based on your troubleshooting, I would agree that there is a fault with the control board.  I attached a picture below.  I'm not sure if this only applies to the PSC models, but make sure there is nothing connected to the CONT terminal on the control board.  (Marked with a red arrow.)

I'm not 100% if the DC MTR terminal (Marked with a blue arrow) is supposed to be constantly powered with 115V, but you may want to check that with a multi meter.  I suspect it's always powered with 115V and the P2 plug powers the ECM fan.

My guess would be the main control fan timer board is faulty.

ICP technical support - 1-800-458-6650

Offline wantcoffee

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Re: ICP C9MPV - Fan Always On - Control Board Question
« Reply #2 on: October 24, 2016, 10:23:30 AM »
Thanks for the quick reply! I will check later on in the afternoon :)

By main control fan timer board  did you mean the large one or the smaller board?

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Re: ICP C9MPV - Fan Always On - Control Board Question
« Reply #3 on: October 24, 2016, 10:28:32 AM »
The large control board - ICP 1172809.

Offline wantcoffee

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Re: ICP C9MPV - Fan Always On - Control Board Question
« Reply #4 on: October 26, 2016, 09:31:48 AM »
Thanks again for your help!

Although the board layout is slightly different than your diagram nothing was plugged to the CONT terminal I went ahead and ordered the board, I am hoping it will solve the issue.