"I just replaced the thermo switch, and the radiator fan *still* doesn't come
on, even with the AC switched on (the AC compressor fan on driver's side
does come on).
I measured the new thermo switch by putting an ohmmeter across the terminals
and lowering it into a pan of boiling water. After the switch closed I got 1
ohm of resistance. The old thermo switch read 8 ohms. So I guess it was bad?
I'm not sure what else it could be.... shorted one side of the thermo switch
connector to ground does make the fan come on while the engine is running.
There's nothing else in the circuit as far as I know.
The temp guage never rises above 1/3 level (so far). Tegger, you had asked
about the heat output in the passanger compartment. At times, it seems to be
normal. Other times, it seems to be cool, even when the temp setting is over
at max. Could this be due to a bad thermostat or something else?"
Personally, I think you're barking up the wrong tree here. 1 ohm or 8 ohms
means nothing. If the temp gauge never gets past 1/3, the rad fan WILL NOT
START NO MATTER WHAT.
If you simulated the heavy stop-and-go traffic like I said for AT LEAST 5
MINUTES, and the temp gauge DID NOT RISE, then your engine IS NOT HEATING
UP ENOUGH to make the fan come on.
I do believe you have a bad thermostat. Replace with new **OEM** for $20,
then report back, BEFORE you spend bigger bucks on the thermoswitch.