heating problem

i have no heat on my side just on passenger side at top warmer and when i put 3 degree less they are nothing .
i change the thermostat,the cooling fluid and i clean the heater radiator.:uhoh:
please help me
thanks

Deville's have driver and passenger controls settings. To make this happen, there are small electric motors which open doors at varying stages to permit more or less hot air to enter on either the driver or passenger side of the car. These "actuators" are known to go bad, and do not open the door for heat. If you have heat on the passenger side, then the driver motor is probably bad. They are interchangeable. Remove the glove box, and panel under the glove box. Your will see the actuators with wires and plugs, as well as rods to the doors (which you can't see). Remove the passenger actuator and swap with the driver side. If you can raise/lower and temp follows....just replace the actuator. I had exactly the same problem and it is quite common.:)