Today the system that serves the showroom was confirmed as having a second stage control circuit failure. The circuit was traced inside the rooftop unit and to the thermostat. I discovered that the thermostat wire that serves the second stage heat was tripping the transformer safety. This was confirmed by operating the system on second stage without the wire in place. A delay timer was installed to serve as the 2nd stage heat thermostat wire and was set on a ten minute delay. The system was operated after the rewire and is functioning properly. The thermostat programming was changed to single stage heating and the second stage heat thermostat wire was removed. It does now cycle between 1st stage and second stage heating via the newly installed delay. Thank you, Jon Tech notes: Trane s/n 22051492JA