Performed furnace diagnostic 2003 Trane split system outside closet. Found gas valve not opening, checked for power at gas valve getting signal. Check control board, everything looks ok took picture. Tested gas valve needs to be replaced. Replaced Gas valve, switched lp kit. Tested system system fired right up. Due to age of equipment want to watch how much money we are putting into it, also keep an eye on the rust and water marks on platform unit has or is leaking water. Equipment operational at this time.