Jesus did predict the coming of the Spirit
“No-one could say that Jesus had failed to forewarn the disciples that the Spirit would come and yet, most of the Gospel accounts of their life after the Resurrection suggest that they did not really expect anything to happen. Two began the journey back to Emmaus, others hid behind closed doors and later went back to the nets they had so impetuously left a few years before. Jesus had told them the Spirit would come - but everyday life seemed to go on as normal and, quite frankly, the disciples were probably glad of the anonymity for a while: As Jesus had also said, ‘if the authorities treat me as they will, how will they treat you?’
“And so, the fishermen continued to fish - and life passed - until one day, they and the other apostles came together. Earlier in Acts, we are told that they met to pray with Mary and ‘certain women’ - a gathering of people who had been with Jesus during his ministry, who had seen him die and seen him rise to new life. What was it in their prayer in that gathering that opened the way for the Spirit to come upon them. As the wind blew through the house - and fire fell upon their heads, did they need Mary to discern what was happening and echo words from her own overshadowing by the Spirit: ‘Don’t be afraid?’
“Suddenly, the prophecy of Jesus in today’s Gospel comes true - the Spirit of truth does come upon the apostles and a secretive gathering of people explodes onto the unsuspecting streets of Jerusalem. There the Truth is proclaimed to anyone who has ears to listen. This Truth is not reserved for a closed group of people but is to be proclaimed to the whole world. The Truth is not limited to a language - everyone can perceive this truth in their own tongue. The Truth is not to be hidden in code - available only to those initiated into its intricacies - but open for anyone who dared to look."
-- (From a reflection on the Gospel by Catherine McElhinney and Kathryn Turner)