I had a very similar or same problem. AC was working great till one day ot stopped blowing cool air in the front, rear was fine but it was the front only that didnt blow.
What had happened was a careless move on my part. I was changing the cam sensor. Once I had completed that when unstalling the dogouse back on, I did not notice I was crushing one of the three vacuum hoses that hang down fron below the radio. There are three vacuum hoses that go from below the dash passenger side to ac control area. I believe it was the black hosethat had a small dent which was enough to ruin it. I ended up carefully finding the damage and made repair to the small hose line and it worked again. I had cool air back on the front of my GMC safari.