How do you change the heater coil for 1998 Cadillac Sedan de

Disconnect the negative battery cable.
Drain and recycle the engine coolant.
Disconnect the heater core hoses using tool J-37097 or equivalent.
Remove the right side sound insulator and the glove box module.
Remove the programmer shield, if equipped, and disconnect the air mix valve link.
Disconnect the programmer vacuum and electrical connectors.
Remove the heater core cover, leaving the programmer attached.
Remove the heater core retaining screws and the heater core.

To install:

Position the heater core and secure with the retaining screws.
Install the heater core cover.
Connect the programmer vacuum and electrical connectors.
Connect the air mix valve link and, if equipped, install the programmer shield.
Connect the heater core hoses.
Connect the negative battery cable and fill the cooling system.
Adjust the air mix valve as follows:

A. Set the temperature on the heater and A/C control panel to 90 °F (32 °C). Allow 1-2 minutes for the programmer arm to travel to the maximum heat position.

B. Unsnap the threaded rod from the plastic retainer on the programmer output arm.

C. Check the air mix valve for free travel. Push the valve to the maximum A/C position and check for binding.

D. Preload the air mix valve in the maximum heat position by pulling the threaded rod to ensure the valve is sealing. The programmer output arm should be in the maximum heat position.

E. Snap the threaded rod into the plastic retainer on the programmer arm. Avoid moving the programmer arm or air mix valve.

F. Set the temperature on the control panel to 60 °F (16 °C). Verify that the programmer arm and the air mix valve travel to the maximum cold position.

Install the right side sound insulator and the glove box module.