My 1999 Buick Regal climate control puts ac out defrost, mid , and floor all the time on auto or manual

There is a thing under your dash called the actuator that tells what blower doors open and close. Like when you put on the defroster the switch it to the floor or vents. Not expensive fix and it`s really helpful to have a shop manual. You can buy chilton or one of the other companys but the shop manual which cost about $20 more tells you every thing about that car. nuts bolts trouble shooting in detail not like the general info from a chilton.
Hope this helps and God Bless :O)

Could be a vacuum actuator problem. or just a vacuum leak, period. I have a Jeep that when it has a vac leak, the climate system defaults to the defrost, no matter what you set it at.

check under the hood for a broken plastic vacuum line near the firewall

GM used an electronic air door actuator on many models to direct the heat and AC for defrost, floor, dash vents, etc. The actuator, which is a small stepper motor attached to a plastic paddle or fin, gets weak with age and use, and the paddle itself can bind or jam. The part is under/behind the dash, and in most cases involves removing the radio, climate control unit, and several plastic panels to access. Allow 3-4 hrs minimum if you have not replaced one before.

Your vent relay switch is bad and you will need to replace it. It is located underneath and behind the glove box.

the motor for the passenger side
blend door is shot

the clicking is caused by a part called a temperature control ac/heater blend door actuator motor, most likely the door it moves is sticking and the little gear drive inside the part is clicking.

Hi,I am Ron,The car manufactures have gone over board with the new way of designing the ac/heater system.They got away from the simple vacuum operating system,and went to actuator motors to open and close ,and blend the air that keeps you comfortable.The problem with your car is in fact,a door actuator motor,that has went out.The actuator motor that you want is located behind the dash,some are reachable threw the glove box(after you remove glove box).The process of elimination is the best way to see if it is the right actuator motor giving problems.You can actually see the actuator motor turn when you select a task for the ac control to perform.Go threw and select one at a time a function for the ac to perform.When you get to the defrost,vent, and floor,look for the actuator motor that does not move.This is the one to remove.It might have three or for screws holding down.This will not be easy to get a socket or wrench on,much less turn the screw.But if you need anymore help,please [email protected]

For a 95 Chevy Silverado....I replaced the Blend Door Actuator on the passenger side. Just behind the slide out cup holder. Yo ucan acces easily by removing the ash tray piece and the glove box....Or just the glove box and work like hell to get a socket in a tight place.

There are 2 actuators....one controlling the (Mode and Temp 89018681) and the other the (Air Inlet 89018367). I called the dealer and the parts were 85-125. I got it From TBA Auto (local store) for 39.00. A 20 min job at most.

You need a temperature control actuator..which mounts on the rh side of the central air con ducting under the dash.Remove the ducting panel on the rh side (3) bolts, then the glove box (2 bolts) then unclip the wiring harness connection box and push aside. Using flashlight look into the center at the central venelation ducting box, on the rh side there should be two raised bolt holes, where the actuator mounts over the white spindle shaft.