It sounds like there is either something wired incorrectly with the thermostat to the control box, or something is not correctly connected between the control box to the Advent rooftop AC unit. Be sure to verify all the connections for the Air Distribution Box w/ Wall-Mounted Thermostat # ACRG15. Check the connectors coming from the air conditioner as well to ensure the terminals haven't pushed out of the connectors. view full answer...