Damien Its a case of buying the new climate and surround then changing some wiresThis is taken from a user called NorthernSky off VWNavi Re: Climatronic on screenI installed the unit and work as expected (mine is VW Jetta GLI 2007 and I did not needed to wire in pararell on Conector C and B)Parts I needed:1K0 858 069 M 1QB Trim5K0 907 044 BT ZJU Climatronic Unit (5K0 907 044 CB ZJU with Heater button)1K0 907 530 AD Can Gateway ('S' revision or later might work also)3C8 937 049 AB Power Electrical Module (For compressor to work) Optional:1K0 907 659 Quality Sensor (optional)1K0 971 939 C Holder (optional)1J0 972 483 A Quality Sensor Conector (optional)000 979 009 E Quality Sensor Wire X2Climatronic WiringOn A Connector (black) extract both; Pin 16 and Pin 20 and put Pin 16 on the place were Pin 20 was, leave the wire on Pin 20 loose (not connected to the harrnes) for later connect the Air Quality Sensor if needed.If you have an older VW Model you will need as user mogwai pointed out this wiring to change:Motors in parallel:On C Connector (brown): Pin 7 connected to Pin 10 and Pin 8 connected to Pin 9On B Connector (black): Pin 6 to Pin 7Quality Sensor Wiring (optional):On C Connector (black): Pin 1 from Quality Sensor to Pin 20 which we replaced by Pin 16 on ClimatronicPin 2 from Quality Sensor is Ground to Pin 19Pin 3 from Quality Sensor to Pin 4 on ClimatronicYOU NEED TO MAKE THIS STEPS as lala30 pointed out (My compressor did not work until I performed the 2 step):First Step: Basic settings: hold button AC + button straight blowing (third button from left). You will see both buttons leds blinking one after another..let them run till they come to the normal status. Reference: http://www.my-gti.com/2513/volkswage...ostics-mark-viSecond Step :Compresor Settings: Starting the engine and hold LONG-AC + heating rear window.Let it run till it comes to the normal status.It says you need the 3C8 CECM but me personally I have a 3C0 937 049E and every thing works fine also bare in mind the surround is on back order at the moment,CheersDarren