1. Allow engine to cool. Using a thick cloth, release pressure from cooling system. Drain coolant from radiator. Squeeze clamps and disconnect heater hoses. See Fig. 141 . Disconnect vacuum hose from water control valve. Cap hoses. Remove instrument panel. See INSTRUMENT PANEL . Remove plenum assembly. See PLENUM ASSEMBLY . 2. Remove Powertrain Control Module (PCM). See POWERTRAIN CONTROL MODULE . Remove ground strap screw and PCM heat sink. See Fig. 142 . 3. Remove 4 heater plenum nuts from engine compartment side of firewall. See Fig. 143 . Remove heater core cover-to-plenum screws. Lift off heater core cover. See Fig. 144 . Remove heater core. See Fig. 145 . To install, reverse removal procedure.