query on 16v rad fan switch...

[tillygti6]

hadnt really thought about this until yesterday, im using one of my old rallye rads with a 16v motor and gti loom, nothing particularly unusual there but ,the fan switch is the 2 pin type for single speed fan speed. i binned the rad off the gti and im presuming it had a 3 pin switch for twin speeds.
the problem being the fan only runs at half speed, am i just being a flid here or is there something else at fault for the slow running?
earths are good, so's the fan when run straight from a battery, so could it be the resisitor? or should it have a 3 pin switch? thats what i reckon anyhow!
any idea people?
tommy

[Gabbastard]

I cant remember how the wiring is on these, but it sounds similar to the heater blower for inside the car - the way the blower runs at different speeds is by more or less resistors being introduced to the circuit. If you say it runs at the right speed connected straight to the battery, Id guess the resistor is causing the problem as all a two pin switch does is complete the circuit.

Take out the resistor (I think they have the big metal canister style ones), bridge the connector and see how it runs.

[tillygti6]

thanks for the reply mate, both single speed and twin speed systems run a resistor of sorts. the fan switch provides signal one way or another, they surely need the resistor to regulate the voltage to the fan or it would just draw a massive current?
i shouldnt have chucked the old gti rad away really!...........

[tillygti6]

anyone else got any ideas? ;)