Markandjulie630

Hi have a fan fault on mk3 mondeo 2.5 2003
Had a quick look at threads and seems quite common fault
Had a look for temperature sensor which feed computer but can't find it and then tested fan power and found red and black feed are permanent feed 12v but small purple wire is not.
Anyone no what voltage should feed down this wire to activate fan and is it the same with joint connect or disconnected.
Also noticed people say the radiator fan should run when a/c is turned on which it don't.
Switched relays around and diodes and all seems well there and tested 60amp fuse which is fine
So wondered if there is an easy way to test fan motor ie put a second 12v down purple wire or take cover off fan switch box?
Also when I find heat sensor can I loop it out or is it resistance based
Has anyone run the fan off a separate switch
One last thing in 2003 I don't think mondeo had an odb2 connection until 2004 like my van ?
All welcome cheers Mark