Armstrong SX90 SX93 Furnace

My friends’ Amstrong furnace wasn’t working a couple days ago. It would seem to start burning natural gas, but then minute the combination blower tried to start spinning, it would make a bunch of what appeared to be clicking sounds before shutting down and not warming the house.

After following the troubleshooting guide in the manual, it recommended replacing the same blower board that was making the clicking noise.

And looking more closely at the blower board, resistor R1 had brown marks all around the board it was attached to. We pulled the blower board out, looked at the back of it, and noticed that the solder connections were cracked – the clicking noise must have been coming from the bad solder connection and the arcing sparks were browning the board over time. Testing the resistor with a multimeter indeed indicated that the itself resistor was fine, just the connection was bad.

A quick visit to Schwie’s Shop for┬ámedicine, in the form of a solder pen, and the board is fixed!

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