Ac comes out windshield and floor vent but not dash vents

the ERG shouldn't have anything to do with what vents the AC comes out of, rather the dash switch that exists for changing from defrost to main vents to floor vents controls what vents are used.

Possible bad blend door actuator .some gm cars can be relearned to the new climate control head

Mode Door 1.
a.This door regulates air flow to either the dash vents or defrost/floor. If you have air flowing only through the vents with no defrost or floor, this door is failing. From our experience, this door is usually the first domino to fail. Not sure why, just is.
<!--[if !supportLists]-->4.Mode Door 2.
a.When mode door 1 is set to divert air away from the vents and into the second stage of the system, door #2 chooses whether air goes to the defrost vents to the windshield or out through the floor vents in the passenger and driver's side footwells. Failure is indicated by an inability to choose between defrost and floor.
b.This door turns out to be the most difficult to replace. In order to replace the door, the dash panel has to be removed. It's still better than the dealer fix because you don't have to evacuate the AC system, drain the radiator, and remove the plenum box. But it is more work than the other fixes. When this door breaks, it falls in the down position, blocking the floor vents and diverting all air through the defrost vents. From a safety standpoint, this is good since you'd most likely rather have a clear windshield than warm feet. We suspect that a large percentage of customers will just leave this door unrepaired. You will have heat through the dash vents and to the windshield, just nothing to the floor. It's inconvenient, but you'll have to make the determination if warm feet are worth the extra work to fix the door. An extra pair of socks is easier.

check for vacuum leak some of the switch are vacuum controled

Your ac blower doors that direct the air to the vents are vaccum controlled check your vaccum lines going to the ac most of the time it is a leak near the vaccum check valve. The reason it is only top vents is because it is the default setting in the system

There is a blend door acuator which moves when u change your settings. Its a electric motor. Down under dash, Will need a mech and a heating and cooling diagram to find where the motor is,

Sounds like a bad actuator on the dampner. Look for things connected to the ducting, see if you can manually open and close the dampner.

The problem is probably a faulty diverter door actuator or vacuum problem at the HVAC plenum under the dash. This is a common problem - see YouTube for help diagnosing this:
https://www.youtube.com/watch?v=Nlt9A1sp-4U

most likley you have a vaccume leak somewhere but also the linkage to the door that that directs the air flow may be in a bind. another possability is the hvac controlls. hope this helps

two issues here. bad servo motor maybe and, jammed lever assembly. i would also check the wire connections for lose and separated connections.


please rate and god bless.