To many steps to list here. I would recomend you purchase a shop manual for that vehicle if you intend on doing that job yourself.
Remove the water supply hoses to your 1998 Chevy Lumina heater core. Remove the heater core retaining bolts. Reverse the procedure to install the new heater core.
You will need to remove the water supply hoses from your 1998 Oldsmobile Intrigue heater core. Remove the heater core retaining bolts. Reverse the process to install your new heater core.
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no the mounts on the core support are differant
go to autozone.com. and click on the heater core part for your sonoma. then there should be an install manual button u click on on the page. i have a 98 gmc wit a heater core out also. i think the 97 models you just have to take off the dash.
Your heater core could be plugged. I've had it happen to a 98 and an 01 S10 pickup. I flushed the core both directions and it heats like crazy now.
There was no rwd Cadillac Fleetwood in '98
Take it to a mechanic.
Under the dash