My son just bought a '97 Jetta GLS. Anytime the key is on the rad fan runs. It appears also to have no tstat, but that's easy enough to fix. The fan seems to only run at one speed. We've driven the car quite a bit but the temp gauge never even gets to 160 and the res never seems to get very hot...thus my thought that it has no tstat. If we turn on the AC, the fan speed doesn't change. It doesn't appear to have been re-wired to bypass the temp switch on the rad...but I know those temp switches usually fail open, not short.
Ideas where to start? Is this maybe a stuck relay? I don't know what all is involved in making it go. Maybe shorted after-run temp sensor?
Someone have a schematic handy for this?