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New owner with a few issues! 1990 964 C4

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Hello everyone, been snooping on here for a while now but I have recently sold my 1982 SC and treated myself to a 1990 964 C4 in guards red. 


Its just been fully resprayed so looks in fantastic condition! Just going to spend some money on new rear lights including the reflector and new front side reflectors just to get the exterior in tip top condition. 


Mechanically she is well. I need to fit a new fan belt tensioner and figure out why the washer bottle low level light is on. 


However my rear head scratching issues, the reason in which I'm here is the CCU unit isn't working as it should. If you put the fuse into no.1 in the fuse box underneath the bonnet the fan blowers will come on straight away regardless of whether its locked, unlocked, ignition on, engine running etc! It will run until the fuse blows after about a minute or so. Its an air con car but I can't say if that works or not. 


I've done a bit of investigation online but soon got bogged down in all this technical data etc - Where can I start first, check the fuses, relays etc?


Any help would be much appreciated.




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