Air Conditioner not blowing "cold" air

[fpilot]

Hi everyone and happy holidays. I recently had my ac worked on because it did not blow out of the center vents. It was repaired and great cold air was blowing out of all the vents but now...having used the heat for a cpl of months and went to using the ac because TX weather is too strange, noticed the air was not cold. Just blew air. Any ideas on what could be going on? Thank you all.