[bmik2729]

I replaced he thermostat to one with a 2.25 degree swing setting and the seeming constant cycling of the unit has stopped. The temp must now drop more then 2 degrees before the heat will come on. I also discovered that the inducer motor was loose and was making a lot of noise and vibrating. I read somewhere that excess vibration could cause the pressure switch to not read properly. I tightened it back up and the unit is much quieter now and vibrates less. All worked flawlessly for almost 12 hours and then it failed to ignite again. All it needed to fire up was to shut the unit down at the main switch, wait 30 seconds (less) and power back on and it fired up as normal. It appears I am going to have to start replacing components. It is a Trane TUD080C936A1 with a WHite-Rogers 50A50-405 controller. Any suggestions are appreciated.