IMPORTANT,make sure you have your radio and alarm codes before disconnecting battery. AS LONG AS YOU DISCONNECT BATTERY FIRST YOU SHOULD BE OK. Did a strip down on valve block this weekend, and put new driver unit in as well. (the flat black unit with electrical connectors and 11 wires running in/from it that is allen bolted onto the valve block under the compressor) Longwinded job as pressure switch was not catered for in socket on new driver unit so out came soldering iron and a temporary connection fabricated!!! HOWEVER ONCE FINISHED, crossed all my digits, reconnected battery, reset windows and sun roof, re-programmed alarm code and bingo..........eas up straight away.........no faults ( so far anyway) just bloody radio ballsed up for the moment as I didn't follow procedure to re code properly[.