Safely transport the vehicle to a dealer's service department or an automotive air conditioning shop where the refrigerant will be discharged from the entire air conditioning system. Unplug the cable connected with negative battery terminal. It is important to drain the cooling system. The process of taking out heater core necessitates removing all components of that include instrument panel and its support beam. Remove the instrument panel assembly. Disconnect electrical harnesses attached to instrument panel support beam using clips. Remove mounting bolts for instrument panel support beam and pull it out of firewall. Note- take your time and don't use excessive force while doing this because there may be some fasteners you might have missed during inspection. Take off plastic cover and disconnect air conditioner lines at firewall, seal openings to prevent contamination, disconnect heater hoses at firewall, disconnect any remaining wiring harnesses from heater unit, remove mounting fasteners from unit, carefully pull it rearward until tubes are free of firewall openings, remove heater core cover then cautiously slide heater core out of heater unit, Be careful not to damage pipes as you slide them out., Installation is opposite as removal was done., Use new O-rings when sealing evaporator refrigerant connections., After installation make sure that all instrument panel support beam mounting fasteners are tightened securely., Refill cooling system and take air conditioning system back to station where discharging took place in order to serve it according to what is required by it.