My ac stays on defrost or floor until i drive for

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.

Some cars use vacuum from the engine to open and close the doors that direct the air to different positions. It is possible that the vacuum line to the controls is cracked or disconnected.

Sounds like the blend door motor isn't working.

go by liquid coolant and check ur heat and ac fan it might be stuck or broken

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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 blend door actuator needs to be replaced. the default setting for the ac system is defrost for safety reasons. the actuator is not working so it stays in the default setting. most times the whole dash needs to be pulled for this motor/actuator to be replaced

There are what they call mode door's these days they have a electrical motor that turnes the door to different posistions...sounds like yours is become broken. It would depend on your expertise in the ac & heating system area to replace the part. Sometimes easy and most of the times the dash has to be removed.

you prob have a vac leak on the back of the intake. good luck

Pull the AC control in the dash and verify that there is vacuum going to it, all the different air diversion doors are operated by seperate vacuum motors controlled by the ac control head in the dash, as you switch it it sends vacuum to the correct location to work that door for the desired air outlet, dash, floor etc..