To make a long story short, removing the heater core on your 1998 Cadillac DeVille involves removing the glove box, the lower insulator, and any components attached to the heater core cover. I am sorry I cannot send you any pictures, you will need to have a look behind the glove box and decide for yourself what the heater core cover is. With the cover off you will then need to remove the heater hoses from the heater core and remove the heater core.
I was told I would have to drop the motor to replace the heater core. I am handy with repair but I'm ready to donate the Cadillac unless I can replace the heater core. The leak is quite bad and I have closed the hoses to the core working from under the hood. Is it a very difficult repair to replace the heater core? I believe I have air pages on both the driver and passenger side. Is there any danger of my setting off the air bag explosion if I make a misstep? If I cannot do the work myself do you know of someone who can do the work? Is it an expensive repair? Sqintly
This information is assuming you have a "Automatic A/C system" if you do not please let me know. HEATER CORE Removal & Installation 1. Disconnect negative battery cable. Partially drain coolant. Remove glove box. See GLOVE BOX. Remove right lower sound insulator. Disconnect electrical connectors. Remove ACM. See A/C-HEATER PROGRAMMER. See Fig. 7. 2. Remove heater core cover. Remove inlet and outlet hoses from heater core. Remove 2 heater core retaining screws. Remove heater core. To install, reverse removal procedure. Fill cooling system. Perform air mix valve adjustment. See TEMPERATURE AIR MIX VALVE under ADJUSTMENTS. GLOVE BOX Removal & Installation 1. Disable air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. Open trap door in rear of glove box. Disconnect passenger-side air bag module wiring connector from retaining clip on rear of glove box. Remove glove box light lens by gently prying release tabs. Gently pry top of switch cover to release tab. 2. Reaching through light opening, push switch outboard. Disconnect electrical connector, and remove switch. Remove 6 glove box-to-instrument panel screws. Remove glove box. To install, reverse removal procedure DISABLING SYSTEM WARNING: SDM maintains sufficient voltage to cause air bag deployment for up to 10 minutes after ignition switch is turned OFF, battery is disconnected, or fuse powering SDM is removed. In order to begin servicing immediately, air bag modules must be removed from deployment loop. NOTE: When SIR fuse is removed and ignition switch is in RUN position, AIR BAG warning light will be on. This does not indicate a system malfunction. Frontal Air Bag System 1. Turn steering wheel to place vehicle wheels in straight-ahead position. Turn ignition switch OFF and remove key. 2. Remove SIR fuse (20-amp) from trunk fuse block, located behind carpet in left front corner of trunk. Remove left sound insulator panel. Remove Connector Position Assurance (CPA) clip and disconnect driver-side Yellow 2-pin connector near base of steering column. 3. Remove glove box. Remove CPA clip and disconnect passenger-side Yellow 2-pin connector. A/C-HEATER PROGRAMMER Removal & Installation Disconnect negative battery cable. Remove right sound insulator. Remove glove box. See GLOVE BOX. Disconnect programmer electrical and vacuum connectors. Remove A/C-heater programmer. See Fig. 7. To install, reverse removal procedure. Actuator Calibration After actuator replacement, actuator must be recalibrated to ensure proper valve travel. Cycle ignition switch to ON position for 3 minutes to allow programmer and actuator(s) to recalibrate travel. For driver or passenger link rod adjustment, see appropriate link rod adjustment procedure.