97 Villager A/C problem

I recently replaced compressor in 97 Villager. When driving on a long trip suddenly the flow from the vents stopped. We could hear the blower and feel a little air seeping around the dash. This only happened on the interstate while we were out of town. At home we could not reproduce problem. It happened again on a short trip out of town, but AC started working fine again after we got home. Anyone got any ideas?