Special custom-built tools are needed to take off trim inside cars made before 2014 without causing any harm to these clips. You will need to have these special removal tools with you while taking apart your vehicle's interior parts. Start by asking a professional to drain out the refrigerant and collect it from your air conditioning system. Separate the car's power from the remote battery anchor point. Drain the cooling system. Twist and lower the heat shield by removing a nut on top of the firewall on the driver's side. Then take off another two nuts that keep the shield attached to bolts on the dashboard. Untighten the bolt that holds the refrigerant lines to the evaporator of the air conditioner. Take off the lines, and extract the seals. Block line openings with plugs or tape to keep out moisture and dirt. Put towels under the tube fits. Remove clamps and disconnect heater hoses from the heater core. Plug or tape over openings to avoid spillage. Lift the heating/air conditioning housing from the instrument panel using the bolts, then peel off the front trim on both passenger and driver sides. Then, take out the front seats. When present, take out and offline the secondary amplifier is the passenger side. Pull out the side trim panels by the B pillar, next to the windshield. Also take off the trim panel directly above the driver's seat. First uncover the floor where the seats meet, then take out the dashboard. Take the shift interlock cable away from the floor duct and move it out of your way. Take out the screws that hold the air duct to the heating/air conditioner housing on the driver's side, and afterwards remove the duct and the tube that drains water from the air conditioner. Use pliers to get rid of the bolts that fasten the left and right back ducts to their housing over the heating and air conditioning system. Take out the dash panel passenger's side heater/air conditioning housing nut, then gently tug the heating system forward and pull it out through the passenger compartment, making sure towels cover the insides to catch any flowing fluids. On a workbench, pry the foam seal from the metal flange that holds the heater core tubes. Then unpin the metal flange from the heater/air conditioning housing and detach it. Untighten and take off the fasteners connected to both the heat core retaining brackets and the heater core line retaining brackets. After that, cautiously pull the heater core out from its place inside the housing. To install a new heater core, you replace the old seals where the fittings connect and fill the cooling system again. You'll need first to drain and flush the cooling system when putting in a fresh heater core.