My experience is with $EE '(94 & '95).
'vettes make use of a separate scalar: 'Fan Vehicle Speed Boundary' in TunerPro, or 'Fan Hi/Lo Vehicle Speed Threshold in TunerCAT.
The vehicle speed boundary...

219°F Lo 227°F Hi = 0MpH
227°F Lo 235°F Hi >0MpH
GM's $EE Y-LT1 fan-on thresholds are identical. The $EE F-LT1 & $EE B-LT1 fan-on thresholds do not change based on MpH, but are also too hot for me....

Don't know about the LT1 OE fan-on thresholds for '92 & '93, but they were set so high from '94-'97 that the powertrain usually runs considerably much hotter in stop'n'go traffic than on the highway....