I have a Trane packaged unit model YCC036-SF-14A. It started not heating when heat was called for or just shutting off with out making set point. I thought is was the thermostat but with a new one same results. It will reset it I turn the thermostat off for 5 seconds then back on. I have no fault codes but the on the igniter board the LED stays on solid red when its in fault.
Would appreciate any advice you can give

Jumper the R-W circuit at the unit and see if the problem still occurs. If not, you have a problem with the thermostat or the wiring between the t-stat and the unit.

Does anybody have the fault codes for this furnace?

Fault code list/label can usually be found inside one of the service panels. In some cases it may be on the circuit board or ignition module housing.