Hi everyone, first post here. Read countless threads regarding my furnace with a three blinking issue. It is a Ducane 80% efficient furnace. Installed ~6 years ago, the tech never registered it so I do not have a warranty. Currently it has an issue where the inducer motor will start and most of the time (70%) I'll get a three blinking LED. This indicates that there is a problem with the pressure switch. Here we go again! [b]What's been done:[/b] - 3 months ago the main board was replaced because it was failing to start (killing the inducer motor after a few seconds, killing gas after one minute, not starting at all, etc and throwing a three LED blink), three LED flashes but the problem behaved differently. It often would flash nearly instantly the three flashes. It worked flawlessly for these three months. a. This is was done after a tech came out and fully looked it over and said for sure it is the main board. b. Verified there is no blockage in exhaust c. Removed inducer motor, lubricated/cleaned and new gasket was made. d. Verified Igniter has ~58ohm, all temp safety switches pass continuity test. e. Thermostat is bypassed during troubleshooting (R and W bridged) f. Thermostat is a Nest. It does have C wire. g. Replacing or bypassing the pressure switch does not solve the issue - Three months later the problem has returned but behaves a bit differently. a. Installed a new main board and the issue seems to be about the same. With this new board I can get it to work sometimes, about 40% of the time. Once the igniter comes on it will work for as long as needed. [b]Video of the problem in action:[/b] [url]https://vimeo.com/519231172[/url] [b]Video of description of what's been done/checked: [/b][url]https://vimeo.com/519228011[/url] [b]Video of it beginning to work, notice igniter glows orange (blooper)[/b]: [url]https://vimeo.com/519232555[/url] Can someone please suggest what I can do next! I'm pulling my hair out, a tech coming out is just going to charge an arm and a leg. The previous tech that wanted to replace the board wanted over $1000 for the job! The part is about $100. [img]https://cimg3.ibsrv.net/gimg/www.doityourselft.com-vbulletin/1210x908/20210303_161336_d9534ecf9754a87ff1c847448b2b18ecfd601e8d.jpg[/img] [img]https://cimg2.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/20210303_165649_a4a83b43679d3e1d57f2b0fe99dacffbc45b58bd.jpg[/img]

Can you please tell us how to relight the pilot light? A breeze must have blown it out.[img]https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/20210310_033350_2__a60a44c12ae98c8adc3476a6463c68ce2c95d112.jpg[/img] [i]Steiger & Kerr Stove & Foundry Co.[/i] [img]https://cimg3.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/20210310_033547_1__bc9e7ae659431e59b5d98b0cf5d8985f5bc2d1bf.jpg[/img] [i]The switch is presently on "Off", which is next to the red-marked indicator on the left. The dial moves freely to position "On" and "Pilot" next to the red-marked indicator, but must be depressed to position "Off" next to the red-marked indicator.[/i] [img]https://cimg9.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/20210310_033420_1__aac193edd5c73b3d2b5762acfe35f299dc250002.jpg[/img] [i]Plate had been painted over, but is partially uncovered.[/i] [img]https://cimg8.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/20210310_040547_1__05c1150daef796bcf6b4f81cc912812e347e54d8.jpg[/img] [i]Access to the pilot light.[/i]