Help I'm trying to determine which hvac actuator controls air flow out of main dash vents on 2008 towncar

SOURCE: There is no air flow

You need part GM Part number 89018675 or ACDelco 15-73596. The Mode Selector Actuator. What happens is the part is a CHEAP part POORLY designed and when it goes to turn the flaps inside the HVAC unit its the plastic gear slips instead of turning the flap!!!

Just to forward you you might want a deal to install this art for you unless your good at fixing your own vehicle, because you need SMALL sockets and a lot of patience to get this part in!!!

The part is ALMOST directly above the steering shaft for your steering wheel, so theres a lot you got to remove before you will even see them!!!

I only recommend you to have a dealer put this part in for you, unless you have your own service manual!!

Because there is 5 of these darn things and if you pick the wrong one you will have to do it all over again!!!

3 on the Drivers side and 2 on the Passengers side!!

But replacing this part SHOULD solve all your problems!! AS it did for me and i was having the same issues as you have described!!

Marvin

• 85242 Answers
• Posted on Oct 17, 2008

SOURCE: how to reset the HVAC

You have a problem with mode mode control switch, it is either leaking vacuum or has no vacuum to it, all of the different modes are switched using vacuum operated air door motors to send air to the selected outlet, i.e. floor, dash. defrost or a mix.

SOURCE: my 2002 trailblazer is making a clicking noise in the a/c

more likely a broken door in hvac case.with car running work controls and watch actuaters operate to locate good luck maybee a little challange

SOURCE: 2003 Trailblazer No air from front face vents

first check to see if you have power going to the actuators when you switch the switch to it location if no power replace controller if you have power and no movement from actuators replace actuator. if actuators move remove hvac box and check for broken blend doors.

Greg Bernett

• 2993 Answers
• Posted on Apr 18, 2010

SOURCE: location and removal of the air vent actuator

Removal & Installation

1. Remove the floor air outlet duct extension from the floor duct.
   
2. Remove the center console, if equipped.
   
3. Remove the screws from the center console duct, if equipped.
   
4. Remove the center console duct, if equipped.
   
5. Disconnect the electrical connection at the mode actuator.
   
6. Remove the mode actuator mounting screws from the HVAC module.
   
7. Remove the mode actuator as an assembly with the actuator cam.
   

1. Install the mode actuator as an assembly with the actuator cam.
   
2. Line up the heater/defroster valve lever with the mode actuator cam slot.
   
3. Line up the A/C valve lever with the mode actuator cam.
   
4. Install the mode actuator mounting screw to the HVAC module and tighten to 14 inch lbs. (1.6 Nm).
   
5. Connect the electrical connection at the mode actuator.
   
6. Install the center console duct, if equipped.
   
7. Install the screws to the center console duct, if equipped, and tighten to 14 inch lbs. (1.6 Nm).
   
8. Install the center console, if equipped.
   
9. Install the floor air outlet duct extension to the floor air duct.
   
10. Calibrate the HVAC module actuators.