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humdinger0102 11-16-2011 08:56 PM

Changing Control Board Questions -- HSI module and AC wire connection

I had a tech come out and say my control board was broken. They were going to charge me $800 so I decided to do it myself. I have a couple of questions.

I have a Janitrol GMP100-3 and am replacing the board with an ICM280 furnace control module.

First question -- The instructions say to "Remove existing HSI module. Note: Do not damage the nylon standoffs." What is the HSI module? I know HSI stands for heat surface ignitor (the element that ignites the flame), but what is the module on the board it speaks about?

Second question -- This new board changes out the red and common blue wires that run to the transformer with ones that go into a 9-pin plug. The common blue currently plugs into a pin labeled "COM" (along with a white wire that runs to the AC) The problem is is that there is no corresponding COM pin on the new board for the AC wire to plug on to. Where do I put this. Should I piggy-back it on to the new common blue wire that will run into the transformer?

Any help is much appreciated!



Doc Holliday 11-16-2011 09:08 PM

HOT surface ignitor. Trace the two wires from the ignitor back to the old board where it's plugged in.

I'm not sure there is a place for a transformer outside of the 9 pin plug on conversion boards. you should have had a few plugs with the new board that you plug the old wires (such as the HSI and transformer) into. Not too sure about the transformer having a plug.

Post pics of both boards and all wires that came with the new one if any. Did it come with any?

Also post pics of where the HSI goes back into the board.

Btw, who told you this new board would work with the furnce?

Doc Holliday 11-16-2011 09:10 PM

My fault, there should be a plug to the hsi a few inches down from where it's installed on the unit. You unplug it there and extend existing wires from ignitor with new wires that should have come with the new board.

Two wire plug.

Doc Holliday 11-16-2011 09:12 PM

The common for the tansformer is going to connect to a spade terminal labeled trnx-h or the likes. Or I think it should. Let me go pull out a board from my truck, it's a nine pin I changed out today.

Doc Holliday 11-16-2011 09:20 PM

Okay,I jumped the gun. The transformer hot is labeled xfmr-h, the common is TR on the plug. At least on this board.
I'd like to know if the board you have is correct for the furnace (as well as take a look at both) but I don't see the low voltage common tied together being a problem.

humdinger0102 11-16-2011 10:13 PM


Here's a link to the photos.

I think I've figured out the HSI issue. I've attached a picture of the old and new board. In the old board you can see the transformer at the top. The purplish wire in the forefront is the "blue common" wire that connects to the old board at the bottom right near my thumb. The red hot wire connects just to the right of that. Those two wires are replaced by the blue and red wires in the 9-pin plug in the new board. My question is about the small white wire that shares a double pin with the purplish "blue common" wire near my thumb on the old board. This white wire runs to the AC. Do you think I should piggyback it on the new blue wire?

The online store said that this board replaces the B18099-06 board, which I currently have.

Thanks again.

humdinger0102 11-16-2011 10:19 PM

Sorry, I meant to say bottom LEFT near my thumb is where the blue common and the white AC wire attach to the old board.

Doc Holliday 11-17-2011 12:16 AM

It appears that I need to sign in to Google to be able to view any pictures and I do not have a Google account or at least I do not remember any of my passwords. :(

But this is the ICM280..

The very first section of this pdf for Goodman (Janitrol) replacement board ICM280 is for your B18099-6. Pay close attention concerning the GMP and GMPV and the GMPN and GMN series directions on the first two lines. Then just follow the rest. It does state that the common need be piggy backed.

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