Serpentine Belt with new AC and new Tensioner on 1990 Chevrolet S10

1988 s10 tahoe 4.3 v6 new air compressor, new belt derailed at compressor within 5 miles, tensioner replaced, belt replaced, belt came off at compressor again within 5 miles.
Both times truck was in reverse backing out, if this makes a difference.

Asked by for the 1990 Chevrolet S10
1 answer
was the ac compressor new or used?? who charged the system?? if it was overcharged, the compressor will lock up and throw the belt. you need to have a shop familiar with ac work to check and confirm.