My Carrier furnace is four-years-old and has stopped heating. I checked the white drain trap next to the inducer motor, and it was filthy but not clogged. I cleaned it, put it back and blew into the pressure valve to check if it's clogged. I can hear it clicking open and closed. I put everything back and started the heat again, but the igniter never lit up. After a few minutes, the yellow light blinks one long, then three short flashes. Do you think I damaged the pressure valve?


It could have already been damaged. When blowing in or sucking on a pressure vale to test it, it takes very little to push it too far. It doesn't take much to pop those in and out, and too much can damage it. If the inducer is running and you don't hear the switch, then it's likely the problem. If you do hear the switch click, on its own, then the igniter is probably bad. The good news, though, is that both parts are reasonably cheap and easy to swap out.

Updated on March 26, 2018

Original Article:

How to Diagnose Furnace Problems & Why Red Light Is Blinking
By Dan Robbins

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