mk2 8v fan not working help please

[PEZ_MK2GOLF]

Hey guys i only have one speed working on my mk2 8v rad fan i have tested and both speeds do work when powered off a live but the faster speed only works when the car running. Anyone know why this could be im just slightly worried about overheating as the fast fan kicks in when the gauge is at the top cheers guys.

[rallye_golf]

More than likely if all the wiring is good, its the thermo switch at fault.
It is down the side of the radiator, check the connections, if they are all good try a new switch.

http://www.vwheritage.com/vw_spares_Therm-switch-for-fan-Mk1-8-81-12-83-Mk2-7-92-3-PIN-191959481C_act_shop.product_pID_48543547_lang_EN_country_GB.htm