Had exactly the same situation with mine.I thought it was some bodge but found out it was factory.The temp switch is located on the back of the head on the left hand side,just above the alternator .A right bitch to get to.I put a new switch in and unplugged the shitty bit of loom and plugged it in the fans.Now works fine.The shitty bodge should only affect the coolant fans,air con fans should come straight on when a/c switch is turned on.