The radiator fan in my 1991 Jetta comes on even when the engine is cold. If I start it to move it across the street, on comes the fan. The climate control is not in AC mode nor on defrost and I've changed the radiator fan switch (this car has a two speed motor, so the switch was the three terminal one). The fan does not stay on but seems to cycle on and off for no apparent reason. It does come on when the engine is hot and cools the radiator OK, but it's the cold temp. operation that has me puzzled.
Where do I look next to solve this problem? Any ideas will be appreciated. Thanks.