Where the Upper radiator hose connects 2 the Engine there is a gooseneck(mounting adapter) take off the housing & there should b a thermostat there IF somebody hasn't removed it.
It is under the dash on the pass side and requires a bunch of work to get to it. Take it to a garage.
Not practical to try to fix a heater core. Replace it with a new one.
I have a 1986 Buick Riviera that the same thing happened to and it turned out to be a fuse blown on the GCC CRT unit. I went ahead and bought a used CRT from a junkyard for about .00.
follow the upper radiator hose to the thermostat housing on engine. Thermostat is located under the thermostat housing.
The thermostat for this car is located in the water pump housing from the lower radiator hose.
The thermostat is almost always located on the top of the engine block, usaully in front of the carberator. Unfortionately, sometimes it is located on the bottom the block
It is in the big water hose on the in side
It is under the intake manafold
On the comp. screen, next to the date, press the little regtangle. This will take you to the screen where you can change both the date and time.
Is on the engine block on the upper water hose.
Mounted in the fuel tank on top.
Its on the front of the Intake. Just follow the top radiator hose from the radiator the thermostat housing.