Try checking the fuses.
on my 98, when you remove the compartment under the steering wheel the compartment has a diagram of all the fuses.
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check heater motor
There was no rwd Cadillac Fleetwood in '98
please tell me how to remove the heater to get too the heater coil
Take it to a mechanic.
Under the dash
Yes, the overhead heater controls do light up.
Probably not.