97 jetta cooling fans

my 97 jetta has been overheating. i'm getting power across the thermo switch to the red/white wire, but the fans will not come on. if i jump the power from the red/white wire to the red/black wire, then the motor turns on, i don't know what to do to get this right. help?

Which engine do you have? Where is this red/black wire, are you sure it's not red/green?

jetta gt with 2.0 gasoline
it may be red/green but my haynes manual wiring diagram(which is a typical diagram) calls for red/black.
it looks as if the wires out of the thermo switch are red/white (for 95 degrees C) & yellow & red and smaller gauge (for 105 degrees C). However the wires on the fan motor are red/white for 95 and red/green or gray for the 105

i'm thinking that the resistor for the low speed fan may be fouled, therefore the power from the thermo switch is not driving the fan. Like I said before I jumped the hot wire from the thermo switch to the high speed side of the fan and it runs.

To complicate matters, I've found that when I jump the power from the therm switch to the red/green or gray side of the switch, that I get no power to the fan motor.

Have you tried running 12V+ from the battery + to the red/white wire on the fan (keeping terminal 3 -brown wire ground) to see if you have low speed? Also, have you checked the fuses on the fan control module (left side of engine compartment by the battery)?

Yes, I have put 12V to the middle terminal (red/white wire) and get no response from the fan. When I put 12V to the remaining terminal (red/green or gray wire) the fan runs fine.
As far as the control module fuses, I have replaced the fusible link & the 20amp fuse next to it is fine.