If the battery is disconnected, several systems must be re-learned before they will work properly. First, disconnect the negative battery cable. Next, remove the center vent assembly; on some models, it may be necessary to remove the radio to access the trim screws for the control assembly. Then, remove the trim panel retaining screws and carefully pry out the panel by removing the retaining fasteners at the top of the center trim panel. After that, remove the control head fasteners and lift out the control head. Disconnect the electrical connectors from the rear of the control head by unplugging all the electrical connectors from the control assembly. The remainder of installation is the reverse of removal.