The factory recommends that the entire instrument panel be removed to remove the heater core on front-mounted systems, as it involves disconnecting numerous electrical connectors and there is a potential for breakage of delicate plastic tabs on various components. This procedure is difficult for the home mechanic and should only be done by an experienced do-it-yourselfer. For Sequoia models equipped with rear heating and air conditioning, the rear AIC unit, which houses the heater core and evaporator, is mounted behind the rear quarter trim panel. Before beginning the procedure, it is important to wait until the engine is completely cool and disconnect the negative cable from the battery. The cooling system should be drained and the refrigerant discharged and recovered by an air conditioning technician. For front-mounted heating systems, the heater hoses should be disconnected at the firewall in the engine compartment, and the instrument panel should be removed. The liquid tube and suction tube should be disconnected from the cooling unit, and the instrument panel reinforcement brace should be removed with the cooling unit attached. The cooling unit should then be separated from the reinforcement brace, and the defroster heater-to-register duct, A/C amplifier, cover plate, damper servo, and upper blower case should be removed. The plastic retainer should be removed from the heater core tubes, and the servo actuator gear should be slid up away from the heater core. The heater core should be pulled from the case and maneuvered out of the unit. For rear-mounted heating systems, the right rear quarter trim panel should be removed, and the bolts from the air conditioning pressure lines should be removed to separate the liquid tube and suction tube from the NC unit. The heater hoses should be removed from the coolant pipes, and the air ducts should be separated from the vehicle. The NC unit case should be removed from the rear of the vehicle by removing the mounting bolts. The blower motor, power transistor, thermistor, coolant pipe, water valve, expansion valve, evaporator, and air outlet servo motor should all be removed. The rear NC unit case halves should be separated, and the heater core should be removed from the NC unit case. The installation process is the reverse of removal, and it is important to refill the cooling system, reconnect the battery, and check for leaks and proper system operation.
Posted by ToyotaPartsDeal Specialist