Re: 1991 SL2 - Electric Fan Speed cutoff speed?

Thanks for your responses, but I still don't know what's wrong:

1. I replaced the fan about 4 and a half years ago.
2. The fan DOES work when the AC is turned on, so its not the fan or the relay.
3. The coolant temp gauge seems to be working fine, so I don't think its the CTS. If it was, it should trip an error code, shouldn't it?

...a failing temp sensor probably won't throw a code because there's not a redundant sensor that can be used as a base measure for the PCM to report against - so whether it thinks it's 90 or 190 degrees only a manual test would determine.

I don't know if this will post right (it's a cut-and-paste from a Word doc) - if it does, this may be helpful. It's valid for ATS and CTS sensors for S-series from 1991 thru 1998.

DEGREES (F)

SENSOR RESISTANCE (OHMS)

-40 77k - 109k

-20 39k - 53k

What year is your car again? Older models have 2 temp sensors - one for the gauge and one for the computer. Your problem most likely lies in the coolant temp sensor.