99 1500..when ac is on or just blowing cold air....when gas pedal is on the floor air flow cuts out totally. when i back off and just cruise the flow comes back.. the freon level is fine and it blows cold.????????

 

search "wild vent's" or "crazy vent's" sounds like you either have a vacuum leak or a check valve is gone..

 

https://dodgeforum.com/forum/2nd-gen...ild-vents.html

 

when the truck is under load it looses vacuum to the vacuum operated vents..

Older cars had a vacuum reserve canister - these vehicles do not..

Mine does it all the time - blowing in your face one second - hit a long hill and it blows to floor - crest the hill and it will blow in your face again..