Have a Trane RTAA 270 (1997) model, controller is the old adaptive control blue screen with four square buttons, up/down/st.pt down and st.pt up. Comp's A & B running fine, but comp C tries to start, then fails immediately on phase loss. The start contactor not even pulling in. Have checked all phases, resistance through contactors, all o.k. C.T's resistances o.k. The oil pressure switch is made. 115v comes from module board on start up, but that's all. Fails immediately on start-up. Anyone have any ideas? Thanks.