Hello
I have a Altra 90 SX Armstrong furnace that has a cycle problem. The model # is a GUK75D103A with a Heatcraft control board 404030001 Cat. # 70K98
The problem that I'm actually having is that it is going through its cycles OK, except the induced fan keeps running and won't shut off.

I am pretty sure that it is a relay sticking and it doesn't look like it can be replaced without changing the whole control board. I searched for a replacement, but none can be found. I am hoping that someone can assure me if I'm on the right track, and if so, they would no where to buy one. Any advise will be deeply appreciated.

Thank you!!
Mark

Does the circuit board have any LEDs that are flashing? This is somewhat unusual, because most circuit board controls will not allow a heating cycle if the pressure switch is already closed upon a demand for heat. If the inducer never stops, that would apply here.

Hello
Here is a photo of my ignition control module, I see no LEDs on it anywhere? The furnace runs fine, its just that the blower runs constantly. I have been searching this site trying to get answers and the closes thing I have come up with is the ignition module.http://imagehosting.fireplaceinstall.net/files/1/ignition1.jpg

http://imagehosting.fireplaceinstall.net/files/1/ignition2.jpg

Thank you !
Mark

In your original post, you stated that the "induced fan" keeps running. Your latest reference was to the blower. Please clarify: the combustion draft inducer, or the indoor circulating blower? The board in the pic is more than just an ignition module; it controls all the functions of the unit. The burned areas on the circuit board, at both ends of the resistor, are an indication that some of the circuitry has been compromised. Go to furnaceparts.com and check their inventory for a replacement.