98 Olds LLC - AC works but fan air does not blow

A vent flap actuator probably needs to be replaced. It's what moves your vent flaps from heat to A/C or to plain "vent air" when you change settings.

The discussion in the link includes vent flap actuators. Unfortunately, they also include the infamous no low speed fan problem too.

Cannot get any air from dash vents while defrost and floor vents work fine...

Your particular actuator will be a different one than they found.
They're all a absolute pain to get at because they can be well buried in the dash. I would start looking under the dash on the passenger side, that's where most of the air control is. Cannot get any air from dash vents while defrost and floor vents work fine...

usually a faulty blend door under the dash

Could be the blower motor, or a restriction in the heater box, or a blend door problem.

I think your problem is the head unit that selects where the air comes out ie. Face, floor, defrost, or hi-level face and floor. If that's not working then it will not let you switch location that you want the air to come out.

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,

There is no vacuum to the controls. Look for a vacuum hose that is no longer connected to the engine intake manifold and repair it.

Your vehicle uses electronically controlled blend doors to direct th air flow from defrost to vent and to the floor . If the door motor is bad then it will stay at a fixed position so you will not get the air to flow out the defrost ducts. There are at least two of these one for air blend and one for fresh air. They are located on the passenger side usually under the plastic cover and have a wire harness that plug in and are usually shaped like a piece of pie.

Hope I was avle to help, glad you up and going.

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

I already posted my solution.