On my '98 MC LS, I am having problems with my A/C. When I am driving it works great. When I come to a stop and then start going again, I am not getting any air out of the vents. After I drive for a block or so, the A/C and/or vent starts to blow air again. What could be wrong? Please advise me of what could be wrong.

i posted on another thread with same problem. 1997 monte carlo.