Replacement of the heater core is a difficult procedure for the home mechanic, involving removal of the entire dashboard, console, and many wiring connectors. If you attempt it at home, keep track of the assemblies by taking notes and keeping screws and other hardware in small, marked plastic bags for reassembly. Have the air conditioning system discharged and recovered by a dealer service department or automotive air conditioning shop. Disconnect the cable from the negative terminal of the battery. Drain the cooling system. The air conditioning unit must be removed in order to access the heater core. Remove the cowl cover. Move the lower dash insulation aside. Disconnect the low and high pressure flexible hoses from the air conditioner evaporator. Plug all open fittings to prevent entry of dirt and moisture into the lines. Disconnect the heater hoses from the pipes protruding through the firewall. Plug all open fittings to prevent entry of dirt and moisture into the lines. Remove the instrument panel assembly. Remove the instrument panel bracket nuts, detach the wire harness clamp, and disconnect the thermo control amp. Remove the mounting fasteners from all four ventilation ducts. Remove the ducts. Remove the side kick plates and disconnect the cables for the fuel filler door and rear hatch/trunk openers. Disconnect the air conditioning drain hose from the air conditioning unit. Unbolt the steering member mounting fasteners and electrical harness clips. Also remove the air conditioning unit mounting fasteners. Remove the air conditioning unit from the vehicle as one complete assembly. Remove the heater packing. Remove the left side floor duct from the air conditioning unit. Remove the heater pipe cover screw and remove the cover. Remove the heater pipe clip fasteners and remove the clips. Remove the heater core bracket screw and remove the bracket. Slide out the heater core and remove it from the air conditioning unit. Installation is the reverse of removal. Do not use old O-rings for the refrigerant lines; replace with new ones and apply compressor oil to them before installation. Refill the cooling system. Reconnect the battery and perform the necessary re-learn procedures. Check for leaks and proper system operation. Check the operation of all electrical components of the steering column and dash. Have the air conditioning system evacuated, recharged and leak tested by the shop that discharged it.
