I had the heater core go bad in my stang a while back and the guy where I took it told me it would be 600 bucks because he had to remove the dash completely. I bought a Haynes repair manual and found out that replacing the core is really quite simple. I dont have a scanner so I am unable to scan the pages, but I'll type it out for you.
Warning 1: The models covered by this manual are equipped with SRS (airbags). Always disconnect the negative battery cable, then the positive battery cable and wait two minutes before working in the vicinity of the impact sensors, steering column or instrument panel to avoid the possibility of accidental deployment of the airbag, which could cause personal injury. Do not use any electrical test equipment on any of the airbag system wires or tamper with them in any way.
Warning 2: The air conditioning system is under high pressure. DO NOT loosen any fittings or remove any components until after the system has been discharged. Air conditioning refrigerant should be properly discharged into an EPA approved container at a dealer service department or an automotive air conditioning repair facility. Always wear eye protection when disconnecting air conditioning system fittings.
Removal:
1. Take the vehicle to a dealer service department or automotive air conditioning shop and have the air conditiong system discharged.
2. Disconnect the cable from the negative battery terminal. Drain the cooling system.
3. On 1994 through 2000 models, disconnect the heater hoses from the heater core inlet and outlet tubes at the firewall. Disconnect and plug the evaporation lines at the firewall. Plug the heater core tubes to avoid spilling any coolant during removal. Cap the evaporation lines to prevent the entry of dirt and moisture.
4. Remove the instrument panel.
5. Disconnect the main vacuum line from the heater/evaporator housing to the engine. It is located above the rear of the right valve cover. Pull the hose through the irewall into the interior.
6. Remove the heater/evaporator housing fasteners, which include a bolt near the center of the unit. a nut at the top right, a bolt near the bottom, and a nut on the engine side of the firewall.
7. Making sure no other wires or hoses are connected to the housing, pull the heater/evaporator housing out from under the cowl and remove it from the vehicle.
8. Remove the four screws and the heater core cover, then pull out the heater core, being careful not to tear the foam sealing material.
Installing heater core:
9. When reinstalling the heater core in the housing, make sure the original foam sealing material is intact and in place.
10. Route the vacuum supply house through the dash panel and seat the grommet in the opening.
11. Position the assembled heater/evaporator unti under the cowl. Insert the heater core tubes, evaporator lines and mounting studs through their respective holes in the firewall.
12. The remainder of the installation is the reverse of removal.
12. Fill the cooling system. Run the engine and check for coolant leaks. Have the air conditiong system charged and check for proper operation of the system.
Well there you have it, hope that helps out some.
