Heater Unit/Core Replacement
NOTE: The battery terminal disconnection/reconnection procedure must be done before and after doing these procedures because some systems store data in memory that is lost when the battery is disconnected.
SRS components are located in this area. Review the SRS component locations, LHD model, RHD model and the precautions and procedures before doing repairs or service.
  1. Make sure the ignition is LOCK (0), then disconnect the negative cable from the battery.
  1. When the engine is cool, drain the engine coolant from the radiator, R20A3 engine model, K24Z3 engine model.
  1. From under the hood, slide the hose clamps (A) back. Disconnect the inlet heater hose (B) and the outlet heater hose (C) from the heater unit. Note the orientation of the hose.
    Engine coolant will run out when the hoses are disconnected; drain it into a clean drip pan. Be sure not to let coolant spill on the electrical parts or the painted surfaces. If any coolant spills, rinse it off immediately.
  1. Remove the mounting nut from the heater unit. Take care not to damage or bend the fuel lines or brake lines, etc..
  1. LHD model: Remove the connector clip (A), the harness clips (B).
  1. Disconnect the connector (C). Remove the clips (D), ducts (E), and the drain hose (F). Then remove the mounting bolt, mounting nuts, and the blower-heater unit (G).
  1. Disconnect the connector (A) from the blower motor. Remove the wire harness clip (B).
  1. Disconnect the connectors (A): The mode control motor, the power transistor, the passenger's air mix control motor, and the recirculation control motor. Remove the wire harness clips (B).
  1. Disconnect the connector (A) from the driver's air mix control motor. Remove the wire harness clips (B), the connector clip (C), and the wire harness (D).
  1. Remove the self-tapping screws and the passenger's heater duct (A). Remove the self-tapping screws and the joint duct (B). Remove the self-tapping screw and the heater core cover (C). Remove the self-tapping screws, the heater pipe bracket (D), and the grommet (E), and carefully pull out the heater core (F).
  1. Install the heater core, and the evaporator core in the reverse order of removal.
  1. Install the heater unit in the reverse order of removal, and note these items:
    • Do not interchange the inlet and outlet heater hoses, and install the hose clamps securely.
    • Refill the cooling system with engine coolant, R20A3 engine model, K24Z3 engine model.
    • Make sure that there is no coolant leakage.
    • Make sure that there is no air leakage.