i have a ac bottle at home with a gauge so i will double check that. only other reason i think its a blend door issue is during the winter i would have the temp set to around 75 degrees for dash and floor vents. and the vent under the passenger seat for the rear passengers would blow at full heat even if i tried cranking it to the lowest temp setting. i also battled this issue last year and most of the time if i adjusted back and forth on temp along with vent position it would work its way out.