Here's a better way to do it. I just installed this on my '91, and it works PERFECTLY! Before installing, my Vette would run up to close to 240 when idling in traffic. Now it turns on the fans REALLY close to the advertised 195 degrees and keeps on going till just a hair below 180, where the fans shut down. Wish I'd known about it sooner.
ECKLER's Corvette Low Temperature Cooling Fan Kit, 195º, GMP, 1984-1995
1991 CHEVROLET CORVETTE STANDARD
Part #: 40416