There is a vacuum switch located behind the dashboard climate control panel. When the vacuum system develops a leak you are unable to change the flow diverter. The part itself is cheap, I paid $17 at a dealer for it but you do have to remove the control assembly to change it out. If you listen carefully you should be able to hear the vacuum leak.
97 cadillac deville heater controll
how do you replace the heater core in 06 cadillac deville
a diagram or a picture of where the heater core is in 1995 cadillac deville is
How do I replace the heater core in my 98 cadillac deville
the fan has a high amp draw roasting the control module replace them both!!
how do you change the heater core on a 99 cadillac deville? I need to know, "Kaiser."
is there a video on remove the heater core on 97 cadillac deville
a "t" in the hoses at the rear, top of the engine has a restrictor built into it no "valve" and no bleeder on this car.
theese are lit by a 16 volt output from the body control module we often find its a bad bcm.
e.g. heater core clogged is a common one - flush or replace it
short circuit in the circuit
if its under the dash by your feet its the heater core is bad