one of the fans spins constantly not shure if its the thermostat thats faulty or a relay and where do you find fuse and relay? how do you disconect the fan wiring to stop it spinning?

its a 1999 2.5 tdi 150

Check at the top of the radiator. There should be a plug to a temp sensor. Unplug that and it should stop. Ps a fan will always spin if you have the aircon on.

had a look cant see the plug(what side is it on ) the only wires i can see go to plugs next to the power steering flud undid them and fan still spinning. just so i know is the fan belt driven?

 Nope not belt driven mate just a electric fan. As far as i know its on the passenger side of the car. Its a temp sensor for the radiator so it has to be plugging in near where the top coolant hose comes in. If its not ill have to do more research but off my memory thats where i thought it was.

i know the bit your talking about but the only temp sensor i can find is one that screws into the block. thinking my thermostat is done but heard its a pig of a job and expensive to do. i know its not ideal to run without a fan but in this weather it should be ok

My fan started running yesterday afternoon after the car had not been used since early morning. Just turned on, Switches off when ignition is turned on then comes back on about 15 seconds after turning ignition off.

Turned climate control off but made no difference. Pulled the fuse out so fans dont run as it killed my battery.

Think it might be a relay but booked into the garage next Tuesday.

where abouts is the fuse for them and how do you get at it? 

On my 2006 A4 2.0 TDI 140 the fuse panel is in the side of the dash on the drives side.  The panel which drivers door shuts against comes out and the fuse on my car is number 4 (5amp).  Not sure if the same on yours, I found it in my handbook.

had a look and fuse 4 is number plate lights couldnt see one for the fan