Having some trouble with this modulating natural gas fired furnace. It's a Coleman, 97.5%. I called tech support and tuned the gas pressure and went over the jumper switches. I went through test mode and fired it in low medium and high speeds and verified proper gas pressures throughout. It runs for about 30 minutes as it slowly stages up from 35% and gets to about 50% and trips on it's pressure switch flashing 3 red lights. Flue looks good, condensate looks good, I checked the orientation of the pressure switches for a horizontal right discharge and it seems fine. It's just frustrating and time consuming to wait 30+ minutes for it to fail, and then I'm not sure if it's the pressure switches or the transducer that's failing. Any ideas?

Posted by Madora at 2025-02-14 19:54:25 UTC