I`m going to start off and suggest this be made a sticky
I don`t care what anyone says Mk3 electronics have awesome electronics, circuits are nice and thick with large resistors and components if you have opened up any cluster,central lock pump, window regulator,and glow plug module as I have you will know its quality.
My A/C was playing up would work for 45minutes then randomly compressor would switch off, then would come back on, so my ac system was working intermittently and unpredictably.
I jumped the A/C Radiator sensor plug terminals with a paperclip and the fan and compressor would come of and on only if I touched the terminals slowly and mad a spark would it work most of the time,anyways if you have this problem or something like it its coming from the relays inside your FCM.
The Fix
So unscrew the screws which hold the fuse strip and unplug the fuses, then break the silicon seal underneath and open The FCM
Then preheat the oven to 240 Degrees Celsius then stick the FCM in the oven on a tray and leave it there for 8 minute,this will reflow the soldier in the curcuit.
Take it out and let it cool.
Resemble and plug it back in.
Vowala
Now I am not going to guarantee that this will work every time and will work for everyone but I was lucky A/C now switches on and off perfectly and has been going strong for 2 months, its worth a try seeing as it cost nothing.
It will work on any of the electronics on the mk3 but be carefull not to leave it in the oven over 8 minutes because there is plastic and it will melt
(I am not responsible if you melt your component to were it wont fit back in it casing or damage the electronic circuitry!)
