Here are the instructions. Looks like you need to evacuate and recharge the A/C, so you may need to take this to a shop with the appropriate equipment to do this job.
1. Disconnect the battery negative cable. 2. Remove the instrument panel from the vehicle. 3. If equipped with air conditioning, recover the refrigerant. 4. Disconnect the liquid line refrigerant line fitting from the evaporator inlet tube. 5. Disconnect the accumulator inlet tube. 6. Drain the cooling system. 7. Disconnect the heater hoses from the heater core tubes. 8. Remove the four nuts from the heater–A/C mounting studs on the engine compartment side of the dash panel. 9. Remove the nut(s) that secure(s) the heater–A/C housing mounting brace to the stud(s) on the passenger compartment side of the dash board. 10. Pull the housing rearward far enough for the mounting studs and evaporator condensate drain tube to clear the dash panel holes. 11. Remove the housing from the vehicle. 12. Lift the heater core out of the housing. 13. Installation is the reverse of removal.