A licensed air conditioning technician must empty the air conditioning's refrigerant before you attempt to take out the front heater core. We do not need to take this step when removing the rear heater core. Pull out the black cable from the car's terminal that holds the negative battery charge. Drain the cooling system. First mark the position of your heater control cable, then remove it from the valve. Take off the heater hoses from where they connect to the heater core pipes at the firewall and close the heater core pipes with plugs to keep coolant from leaking out while you remove the heater unit. Remove the inlet and outlet hoses attached to the evaporator lines at the wall between the engine and passenger sections. Unscrew the nuts that hold the heater core and evaporator housing in place by the firewall at the engine front. Remove the instrument panel. First undo the bolts that fixed the evaporator housing to the heater housing. After that, pull the evaporator housing off. Loosen all the mounting bolts on the heater core housing. Then take care to move the assembly safely out of the passenger compartment. When ready, loosen and remove the straps that wire the heater core pipes. Gently remove the heater core from its place by holding it by the edges to let it cut free from the wall seal. Put the heater core and evaporator hoses back into place on the engine bay wall, just like when you took them off. Plug the cable back into the negative battery terminal and top up your car's cooling system. Ask the mechanic who took out your air to check and fix any leaks in your air conditioner. To get to the rear heater core, you must take out the middle console. Carefully take apart the heater hoses from the air conditioning/heating unit on the car's backside. Put a thick towel and plastic under the connections to gather any leaking coolant before you disconnect. Detach the two belts and the clamps that hold the pipes in position to free the heater core and right air conditioning/heating housing. Push up on the housing's right side only until you can take the water core out, and loosen the left side mounting bolts if needed. Installation is the reverse of removal. Plug the battery cable back to the negative terminal and top up the cooling system. Ask the store to check and test for leaks after they clean out your car's air conditioning system.
