How do I remove and replace heater core in a 1993 Cadillac Coupe DeVille

SOURCE: How do you replace a heater core in a 1991

well i remember that wonderfull day when i got my first heater core job at the Dealer it was a 91 deville. lets just say u never are a happy person when you have to pull the entire dash asm atleast back on the passenger to get the hvac case out of the car. if you havent done anything near that i would say it would take you maybe a few days to a week to finish it. icould do them now in about 6hr-8hr. so the dealer would charge about 1100-1300 bucks. ill do the job 4 6 hundred/ 562/587/8001

SOURCE: heater core

Ok to replace the heater core in the allante you must first take the door off the glove box by removing 4 screws in the corners by the hinges. Remove the valence below the dash on the passenger side.

Now follow these steps

1. remove the radio module disconnect all wires and set it aside
2. Remove the bracket that holds the engine control module slide it out and away
3. Remove the duct control unit slide it down and out from under the dash
4 remove the screws that hold the duct work together, rotate to right and then down from under the dash
5. After the prior the heater core is in view. it has two 8 mm screws holding it in place remove them
6. Now go under the hood with a long extension loosen the clamps on the heater core
7. with at least a 12 inch thin bent flat screwdriver at a 90 degree angle loosen the hose and wiggle it off the heater core nipples
8. Go back into the cockpit and remove the heater core by sliding rearward and to the right
9. Angle hater core down and slide out.
10. reverse to reassemble.

SOURCE: How to remove and replace a heater core for a 1998

if I remember correctly the engine has to be removed.