MY 99 buick is having problems with the distribution of the heated air to the vents, on the driver side the air flow is hot and weak, but on the passenger side the air flow is strong but cold, also on the display of the heater and airconditoning control panel, the temperature figure flashes. Is it the vacuum lines, or is it the control panel ??????
How expensive depends on which climate control system you have (Manual or Automatic). From what I've read, Manual has one temp actuator on the heater box behind the glove box. Automatic has two temp actuators, one on either side of the heater box.