2 Answers

Instructions
Removal

1
Disconnect the negative battery cable and wait at least one minute for the air bag system to lose power. Make sure the front wheels are straight ahead and lock the steering column.

2
Detach the air bag module by removing the bolts from underneath both sides of the steering wheel and the electrical connector. Remove the steering wheel bolt and press the wheel away from the steering column. Remove the lower steering column cover.

3
Insert a 1/8-inch wire or pin punch in the shroud hole under the ignition switch while it's in the "Run" position. Press on the pin and pull on the ignition switch lock cylinder to remove it.

4
Disassemble and remove the instrument panel from the Taurus' interior. This includes the radio and all panels, electrical connectors, harnesses and screws. You'll need an assistant to help you lift and remove the instrument panel.

5
Drain the engine coolant from the cooling system, using a clean container for reuse. Remove the heater hoses, actuator and metal cover from the heater. Disengage the spring from the heater core cover and the lever.

6
Depress the locking ramp and remove the lever from the secondary air temperature control (the lever is brittle, so don't bend it). Remove the primary air conditioning air temperature control door shaft from the pin.

7
Remove the heater core cover and seal from the heater/air conditioning housing assembly. Remove the heater core from the heater/air conditioning housing by pressing on the core tubes and assembly.

Installation

8
Install the replacement heater core to the heater/air conditioning housing. Install the core cover, seal, lever, spring, metal cover, actuator and heater hoses.

9
Replace and assemble the instrument panel with your assistant's help. Connect the steering wheel (use a new bolt to connect it to the column), air bag and negative battery cable.

10
Refill the cooling system with either the old coolant or new. Start the Taurus' engine and let it reach normal operating temperature. Watch the climate control operation and check for any leaks.

Read more: How to Replace the Heater Core in a Ford Taurus | eHow.com http://www.ehow.com/how_4521301_replace-heater-core-ford-taurus.html#ixzz2GNFDq1S7

Take the car to a dealer, WBMS

It is a big job, the dash must be removed to get to the plenum where the core is located