Removing and replacing heater core on a 92 Oldsmobile Cutlass Supreme S, 3.1 engine, LHO VIN T. Down below in bold, and underlined is what I don't completely understand from the repair manual. "Disconnect the negative battery cable. Properly drain the engine coolant into a suitable container. Remove the upper weatherstrip from the body. Remove the upper secondary cowl. Remove the lower secondary cowl upper nut. Disconnect the heater hoses from the heater core."