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How to Change a Heater Core in Toyota Cars

by Contributing Writer; Updated June 12, 2017

You may also have a heater core problem no heat is entering the cab of the truck when you know the thermostat is good and you have plenty of coolant in the engine. This project can become a bit involved; set aside a full day to complete it to avoid the need to rush.

Under The Hood:

 How to Change a Heater Core in a '92 Toyota Pickup

Removal

Pop the hood on the Toyota pickup, and disconnect the negative battery cable by loosening the terminal nut with a wrench. If your truck has an air conditioner (AC) installed, discharge the AC system properly using an approved fluorocarbon recovery kit. Do not discharge the gas into the air.

Drain the coolant into a drain pan by opening the valve on the bottom of the radiator using a wrench. Put the drain pan up and out of reach of children and animals. Label the hoses to the heater noting their correct locations with a marker and masking tape. Disconnect the hoses using a screwdriver to loosen the hose clamps.

Remove the instrument panel inside the cab of the truck, using a wrench to loosen the bolts. Look for most of the bolts around the bottom perimeter of the dash panel. You may find several in the glove box as well.

Disconnect the ductwork from the heater unit. (You may need a screwdriver to assist in disassembling the ductwork.) Unhook the springs connecting the control cables to the heater unit. Take care not to kink or otherwise damage the control cables. Unplug the wiring harness from the heater blower.

Remove the four bolts mounting the heating and cooling unit to the firewall using a wrench. Pull the unit away from the firewall into the passenger compartment of the truck. Despite the fact that you have drained the cooling system, a significant amount of fluid will remain inside it. Clean the area with old towels.

Remove the bolts holding the heater core to the unit using a wrench. Slide the heater core up and away from the heater unit.

Installation

Slide the new heater core into place on the unit, and tighten the fasteners with a wrench. Push the heater unit into place on the firewall, and install the mounting bolts. Tighten the bolts with a wrench.

Connect the control cables to the heater unit, hooking the springs into place. Take care not to kink or damage the control cables. Connect the ductwork to the heater, snapping it into place.

Install the instrument panel, and tighten the retaining bolts with a wrench. Connect the heater hoses to the heater core in the engine compartment, and tighten the hose clamps with a screwdriver. Refill the radiator and reservoir with engine coolant.

Recharge the air conditioner with approved fluorocarbons if you have an AC unit. Connect the negative battery cable, and tighten the terminal nut with a wrench.

Start the Toyota, and allow it to reach operating temperature. Check the system thoroughly for leaks in the engine compartment as well as inside the truck cab.

Items you will need

  • Wrench set

  • Fluorocarbon recovery kit

  • Drain pan

  • Marker

  • Masking tape

  • Screwdriver

  • Old towels

 How to Replace the Heater Core in a Toyota Camry

Drain the Camry's engine coolant, using a clean container for reuse. Disconnect the negative battery cable and wait a minute and a half for the airbag system to de-energize. Discharge and recover the air conditioner refrigerant.

Disconnect air conditioner suction hose and liquid pipe, then clamp on the tubes with an SST clamp. (Make sure you don't deform the tube). Disconnect the heater core hoses.

Disassemble every component of the dashboard, starting with the steering wheel and column. Removal includes the door scuff plates, cowl side trim, console panels and air bags. You'll need a second person's help to remove the dashboard from the interior.

Remove or disconnect all air ducts, the heater blower assembly, lower defroster nozzles, air conditioning radiator assembly. Remove the mode damper servo sub-assembly and Airmix damper servo sub-assembly, then remove the core from the air conditioner assembly.

Install the replacement heater core into air conditioner assembly. Reassemble all components of the heating/air conditioning unit, dashboard and dashboard components. Connect the heater core and A/C suction and pressure hoses, lubricating the O-rings with compressor oil.

Attach the negative battery cable, fill the cooling system and evacuate and recharge the air conditioner. Start up the engine and check for leaks in the system.

Items you will need

  • Replacement heater core

  • Wrench

  • Screwdriver

  • Clean container

  • SST clamp

 How to Replace the Heater Core in a Toyota Corolla

Remove the Old Core

Unplug the Corolla's the negative battery cable and wait 90 seconds for the air bags to lose energy. Drain the coolant from the cooling system, disconnect the heater hoses and discharge the air conditioner refrigerant.

Take out the driver air bag by loosening the screw covers on the steering wheel and the module-to-wheel Torx screws. Remove the steering wheel nut and press the wheel from the steering column. Remove the glove box and passenger air bag.

Detach the steering column. Remove the front door scuff plates, cowl side trims, front pillar garnishes, lower finish panel, hood lock control cable, lower insert, cluster finish panel, steering column cover and combination switch, heater-to-register duct, combination meter, column-to-dashboard fasteners, and steering column shaft pinch bolt.

Disassemble and remove the dashboard. The lower left and right side panels, shifting hole knob or bezel rear console box, center lower cluster finish panel, stereo opening cover, lower center finish panel, air conditioning panel, center cluster finish panel, radio, and electrical connectors.

Disconnect the evaporator housing. Remove the heater-to-register duct, lower defroster nozzle, braces, reinforcement. Disconnect the cruise control actuator connector and set bolts and the refrigerant line clamps. Remove the tube and drain hose grommets, air conditioning amplifier and the evaporator housing.

Remove the rear heater ducts by pulling back the carpet. Remove the heater housing by disconnecting the wiring harness, housing-to-chassis nuts and the heater housing. Remove the air duct from the housing, then the heater core from the housing.

Install the New Core

Install the new heater core, attach the air duct and connect the housing back to the chassis. Install the heater ducts and replace the carpet.

Reinstall the evaporator housing, dashboard, steering column and air bags into the Corolla. Perform everything from Section 1 in reverse order.

Connect the heater hoses back to the core. Fill the cooling system, reconnect the battery cable, then evacuate, charge and leak test the air conditioner refrigerant.

Items you will need

  • Replacement heater core

  • Wrench

  • Screwdriver

  • Torx socket wrench

  • Steering wheel puller

  • Liquid line tool

  • O-rings

  • Engine coolant

 How to Replace the Heater Core in a Toyota Highlander

Rear Heater Core

Disconnect the Highlander's negative battery cable. Drain the engine coolant into a clean container if you want to reuse it. Disconnect the heater hoses from the rear heater core.

Take out the front seats, front, rear and lower door scuff plates and the cowl side trim. Remove the rear console box and the left side air outlet grille.

Pull the carpet toward the rear. Remove the air outlet grille and rear air duct and disconnect the electrical connectors.

Remove the rear heater housing and the heater core-to-heater housing screw and plate (by disconnecting the screws and clamps). Remove the heater core from the housing.

Install the replacement heater core into the housing and connect the housing screw and plate. Reinstall the rear heater housing.

Reconnect and install the electrical connectors, rear air duct, air outlet grilles, rear console box, door scuff plates, cowl side trim and the front seats. Connect the heater hoses back onto the rear heater core.

Refill the cooling system, using fresh coolant if the old coolant does not appear good. Reconnect the negative battery cable.

Front Heater Core

Unplug the negative battery cable, drain the coolant and disconnect the heater hoses from the core.

Detach the steering wheel. With the front tires facing straight ahead, remove the wheel side covers and screws at each side. Remove the air bag module and unplug the electrical connector, then remove the wheel nut. Place alignment marks on the wheel and main shaft.

Pull out the instrument panel after disconnecting all components on the panel. This includes the front door interior, steering column, hood lever, glove compartment, center console, clock, radio and heater controls and the audio amplifier.

Discharge and recover the air conditioner refrigerant. Remove the evaporator housing after disconnecting the refrigerant lines and electrical connector. Remove the defroster nozzle, theft deterrent, wireless door lock ECUs and the air duct.

Remove the heater housing from the chassis, the cover from the housing, then remove and replace the heater core.

Reinstall everything in reverse order of removal (heater housing, defroster nozzle, evaporator housing, instrument panel, steering wheel, heater hoses). Fill the cooling system and reconnect the battery cable.

Evacuate and charge the air conditioner. Run the Highlander's engine until it reaches normal operating temperatures. Watch the climate control operation and check for leaks in the system.

Items you will need

  • Replacement heater core

  • Wrench

  • Screwdriver

  • Engine coolant

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

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