Ater hoisting-had it up 12 hours,when lowered, front end went flat on the floor.( both front air suspensions). Replaced front and rear shocks recently(60000miles) Reprogrammed and suspension ok,but getting intermittent hissing sound from r front area of car. Is this a sign of the compressor failing or what? Any ideas would be helpful.

 

The compressor and release valve along with the valve block are at the rear of the vehicle, so any "hissing sound from the right front area of the car" would be an air leak in the right front strut or the line feeding it, did you put the vehicles suspension into jack mode before placing on the lift ?

 

Is the car dropping at any point especially over night? If not, its not your suspension.
If it does do a few checks before you spend any money on a shock.

Using soapy water check the area when the air line connects to the shock. Sometimes you get very lucky and its just this rubber seal thats gone. I had that a year ago. Also check which side is dropping first. I've found when my front right unit fails it will actually drop on both sides.